The largest area of repair is to recondition or rebuild a piano.  These terms are subjective, yet the Piano Technicians Guild defines (read more here)

On very rare occasions is it feasible to replace or restore ivory key tops to a piano - the report below goes through considerations and what it takes for this big job -

Ivory Key Top Restoration

Sometimes it becomes necessary to replace the keytops of a piano - too many chipped and broken keytops, or they become discolored.  I have even had some that a young 5 year old artist decided to draw on them with a magic marker.  One of the joys of playing piano is the touch and feel of attractive, good  looking key covers.  To find out what's involved with getting a new set, check out the file below:

Key Top Replacement

This is the final step - putting it all back together again.  As you watch the video, you'll notice Jamie wears at least 2 different outfits through the video -- that means it took at least two days to put it all back together.  That doesn't include the time spent back at the shop - it takes time to do things right, and that's why I'm glad Mr. Musselwhite put together these videos of showing just the work it takes on the action and keys of the piano.

Regardless, there's much to a truly reconditioned piano, be it an upright or a grand piano.  The value in this work will be music, a lot of fun and a joy for many years on this old upright - recondtioned - piano.