Finding a good replacement paint should be easy, there are several very good interior paints on the market. My favorite is Benjamin Moore Regal.
The color of your current paint can be matched by any good paint store, not a problem, but an exact sheen match isn't possible. This won't be too much of a problem for base boards but vertical surfaces will show if you try touching up the original with a new paint. After choosing a good replacement paint you will need to use it on a room by room basis.