Like Chopin, never play it the same way twice.  This article from Bulletproof Musician is fabulous.  The popular posts on the right side bar look great as well. 

Excerpt: 

How to Keep Performances of the Same Piece from Getting Stale

by Dr. Noa Kageyama


More engaged musicians

A trio of researchers (including conductor Timothy Russell) ran a study to see if a more mindful approach to performance would be a) more engaging and enjoyable to the musicians, and b) preferable (and noticeable) to listeners as well.

To test their hypothesis, they recruited 60 members of a college orchestra to perform the finale from Brahms’s Symphony No. 1 two times.

The first time, the conductor gave the orchestra the following instructions: “Think about the finest performance of this piece that you can remember, and play it that way.”
This was the control condition – where musicians were given an aspirational and presumably motivational goal, but a comparatively passive goal, geared more towards recreating a performance than creating it anew in the moment.
Before the second performance (the experimental condition), the musicians were instructed to “Play this piece in the finest manner you can, offering subtle new nuances to your performance.” The idea with these instructions was to get the musicians to be more present and mindful, to think more creatively and spontaneously in the moment, and be more improvisational in their performance.

To gauge the impact of these two sets of instructions on the performers’ level of engagement, the musicians were asked to rate their enjoyment of the performance after each run-through.

Not surprisingly, musicians rated the more mindful, improvisational performance as being more enjoyable. The results suggest that being more actively involved in creating something new is more engaging than striving to recreate something from the past.