I may have blogged this before but, if so, it's worth repeating...
Do you have a short, tricky passage in a piece you're preparing?
Perhaps something with weird intervals or awkward notation?
1. Memorize it
2. Cut a little piece of a post-it note and cover that part of your music
3. Play the piece and, when you get to that tough passage, play the memorized lick.
Seems to work.