Great question.  Everybody burns out at some point in their playing life.
The key is to change your routine(s), at least temporarily.  Here are some
strategies that I've heard of - 1, 2 and 7 have worked for people I know.

1.  Take a 3-4 week vacation from playing (anything!)

2.  If your playing is 90% solo; find compatible ensembles or a partner to
play with - or if your playing is in an ensemble, work on solo performance.

3.  Play great folk and pop songs STRAIGHT for a while - concentrate on
the melody, phrasing and basic harmony - no improvised solos, no altered
chords, no extra ornamentation, no rhythmic rearranging etc.  (You might
check out the last Keith Jarrett recording.)

4.  Start learning a new instrument or (if you don't compose already) start
composing.

5.  If you play at home all the time, get out in front of some audiences;
if most of your playing is for audiences - spend more time at home playing
for yourself.

6.  Arrange some arias for piano - again, play them pretty straight.

7.  Talk with a good therapist about music and things in general.

Reid McLean / [log in to unmask]