BartK I'm not saying this to discourage anyone but just to point out that it's completely untrue that the more advanced you are the fewer pieces you can do. It's very easy for someone advanced to pick easy pieces; so easy that it's no problem at all to learn them in a few days. If you think you can't do it because your pieces are getting more difficult just pick easier pieces.
Also, from what I've seen on piano exam syllabus lists, smaller sections, such as movements of sonatas or other lengthy more advanced pieces are treated as stand-alone pieces.