When I was in the hospital having surgery they provided me (and all
patients) with disposable bed pads.  These are plastic on one side and an
absorbent material, cotton, on the other and you use them cotton side up.
I'm sure you could find these or something like them somewhere.  Just keep
some stored under your new sofa and when kitty jumps up place on under
him/her - or keep them spread over the sofa unless company is coming over.

Hugs,

CatNipped