It sounds like you're looking for the RV Rubber Roof Cleaner # BE82FR which is a sealant conditioner and will protect your work.
If you're interested in replacing the roof with another synthetic rubber then you'd also need the Alpha Systems Superflex TPO RV Roof Membrane # AL68CV which can be cut down to fit, and the Alpha Systems 8011 Adhesive for RV Roofs # AL27CV. view full answer...