I think you should always be aiming to mot only improve, but evolve your game (two distinct concepts right? I think so anyway)
It's pretty easy to say you're going to train with the mindset of improving yourself. Whether it's conditioning or technique. But what about evolution? When do you think that your current arsenal is getting outdated, figured out, not as complementary to the rest of your game as you thought? I think that's a really hard question to ask and answer.
Imo though you know by how you do in competition. If you're not a competitor then I dunno why you would care about evolution so much.. But what if you're the champion all the time. Then how do you know it's time to change things up? When you lose? Or beforehand. 
I feel like if you aren't competing any time soon that it's the perfect time to "evolve". That's the beautiful thing about BJJ, you can add or subtract things at any time. But I feel that off season playing around with new moves is the best time. For me, once I got my purple belt I devolved my game. Went back to the bare bones basics. 
I agree with you I think. Regarding the basics, I think a lot of competitors don't necessarily have a strong fundamental technical base, and they try to make up for it by trying to add the most modern and tricky techniques to their game. It's like somebody for instance who idolises the Mendes brothers and drills berimbolo sweeps all day.. But his fundamental understanding of DLR is lacking. It's almost like some people try to mask their lack of a mastery or understanding of the basics by trying to play with techniques and positions that they are hoping their opponent either hasn't encountered or doesn't know how to shut down.
When you get bored, I don't know how guys play the same game over and over for so long
im guilty of this. berimboloing as a blue and my instructor said nice. but later in class He said how good can it feel to tap someone with crazy techs but not being able to armbar a white belt. he was talking about someone else in class but it made me think.
His advice was every roll only use tech that was one stripe above the partners level so you are not learning how to do advanced moves vs lesser partners that is what drilling is for, but said vs your rank or higher everything is game.
this lets both partners hone their skill and not try to trick each other with the most secret tech.
If i berimbolo a white belt it doesnt help me as much as trying vs someone who knows what to do. and it doesnt help the white belt bc he doesnt know what happened. but if i armbar or triangle him he knows what he did wrong and i am sharpening my skill vs someone who knows what is coming.
that said it is sooo hard not to sometimes ;)
Usually it will just happen when you hit a certain level. Or when you use certain elemental stones, or trade moves.
biggator - im guilty of this. berimboloing as a blue and my instructor said nice. but later in class He said how good can it feel to tap someone with crazy techs but not being able to armbar a white belt. he was talking about someone else in class but it made me think.
His advice was every roll only use tech that was one stripe above the partners level so you are not learning how to do advanced moves vs lesser partners that is what drilling is for, but said vs your rank or higher everything is game.
this lets both partners hone their skill and not try to trick each other with the most secret tech.
If i berimbolo a white belt it doesnt help me as much as trying vs someone who knows what to do. and it doesnt help the white belt bc he doesnt know what happened. but if i armbar or triangle him he knows what he did wrong and i am sharpening my skill vs someone who knows what is coming.
that said it is sooo hard not to sometimes ;)
Wow thanks for this training tip. Great advice from your instructor that ill certainly begin practicing (the advice on rolling with lower belts)
I figured it was time to evolve/ move on once I was learning more from another purple belt and mginaction than my instructor.
I can't qualify when to evolve in words. In my opinion, you just know. Like right now, it feels right for me to work on something very specific, something that I never used to do very well. I've thought about working on this development in my game for a while, but it never felt right. Now it does.
When your class mates learn to see your techniques coming.
I was hooked on the loop choke for ages. ans was getting everyone with it. but the problem was that my guard was getting past too easy if I didn't sink the choke in. so then I worked on my guard retention. so now my guard is that little more difficult to pass. so I can feel a little more comfortable attempting subs
To me, evolving your game is adding techniques to your current game to deal with new things people are doing to attack/defend against you.
Personally, I identify problems after doing a competition and/or rolling with someone new. When you roll with people outside of your normal rolls you will find people who things differently and that difference can cause problems for you.
Once you've identified X technique, it's time to figure out how to defend against that and it will make your grow and evolve.
To add on what Wutang said, its always interesting how your game changes and what you add to 'beat' the guys you train with all the time because that's the majority of your rolls and they know your game best
So you devolop this certain set of techs that work on the guys that counter you at the gym but when you go against guys outside your gym or comp the same "old stuff" usually works and you didn't need the other stuff
Even Marcelo said before the last ADCC or 2009 he didn't think his guillotine would work because his guys got so good countering it at his school because they see it all the time and he guillotines the first 2 guys I believe
Mr positive - To me evolving your game is making what you do well even better.
Agreed.
When shit stops working, it's time to evolve. For a while I was catching brabo chokes on everybody, but pretty soon my teammates caught on, so I had to make my arm-in guillotines and other chokes better.