It might just not be enough to repeat something over and over.

play games with yourself so that the instant you play that idea again. you did it a bit better than you did last time.

dont just repeat. improve.

1. example: a lick you are trying to work up. find a tempo that works. instead of repeating that lick over and over at the same tempo. increase the lick 1 bpm so that you are better at playing the lick at a beat more than the last time you played it

also if you nail it then increase 1 bpm, if you fail then decrease it 1 bpm