Seeing a concert of a great musician always inspires me to play and work harder,
and second best is watching a video of a concert or an interview of a great musician.
These almost always make me fall in love again with playing.
Not sure why, but this one always works: (Nikolai Luganksy in Tokyo)
http://www.youtube.com/watch?v=jYCGcM83s2w
Here's one that as worked for me for ever:(Glenn Gould playing Aria from Goldberg V.)
http://www.youtube.com/watch?v=Gv94m_S3QDo
Here is one that shows that even the great masters have to work really hard:
(Jorge Bolet's masterclass for the Rach Piano Concerto No. 3, if you have time I recommend
watching all 13 parts of this one)
http://www.youtube.com/watch?v=CnyvFpP30bs
For some reason seeing the music being performed works more reliably for me than just
hearing it.
Another thing that works for me is to read about the pieces I am trying to learn or would
like to learn. However, I have found reading books or watching biographies about the composers
has entirely the opposite effect. These tend to depress me more because the books
confirm that the great composers had something god-given which can't be learned through
hard toil of playing arpeggios and scales.
I know you have exams coming up so I don't know if you have time to spare, but also taking
and extended break has always helped me to refresh. Taking a day or two off completely
without touching the instrument at all, not even for fun, always helps me.
I hope these help! Good luck with your exams.