One of the best things you can do to improve your jiu-jitsu over time is to keep a journal. But rather than keeping track of everything that happens, only write down the things that worked well: the successful sweep or guard pass, the incredible stamina that made you feel like you could train forever that day ... Whatever is working, you make sure you note it in the journal. You can be as celebratory (though please don't be an ass) or as a matter of fact as you want in describing the event. But the journal should include nothing but success after success after success.
Dealing with your weaknesses is important. But there's nothing more important than being good at what you are good at. If you don't know what you are good at, then this is a very straightforward and practical way to both find out and remember.