Kitchen Cabinets

I live in an older home where the cabinets are built right into the wall. If that makes sense.

Anyway they are made of plywood with a maple finish. I wanted to freshen them up an modernize them somewhat. Would you suggest stripping them and refinishing them that way? If so, what is best to use.

I also considered just cleaning them up real good and someone suggested TSP. Now will that strip the wood or just clean the wood? Any suggestions would be helpful. At this time I cant afford new cabinets. Theres 26 knobs on these things so that tells you there are lots of cupboards. Thanks