Dear 100 Hour Board,
Earlier in the year, I had to learn a ton of piano music for an audition. The audition is over now (thank goodness). I love these pieces and want to keep them in my repertoire. However, every time I practice them, it seems like they're getting sloppier and I'm forgetting a lot of the notes. How can I keep my pieces fresh, lovely and memorized?
The Whole Nother
I too experience the overpractice fatigue you described. What generally helps me when I get to the point where repetition is only wearing at my performance quality is to put the piece aside for a while. Playing it through once or twice every once in a while, perhaps even from the sheet music rather than from memory, keeps it fresh. And if you do need to publicly perform the work again, the heightened concentration from the social pressures will dispel the effects of overpractice fatigue and your performance will still be lovely.
Keeping it memorized is the hardest for me. I tend to unconsciously make up fills for parts I've forgotten, especially in the left hand. After two years of no classical piano as a missionary, I forgot everything I had memorized, but playing it through from the sheet music brings it back quick. In fact, by forgetting and relearning those pieces I actually polished them a lot more than if I had just continued to practice them.
In sum, a periodic review will keep the music you worked so hard to perfect in performable condition, but losing those pieces isn't something to stress about, because once you've learned a piece it is easy to recover.