Do working pensioners pay social charges?

I AM on a low income following a divorce that came after I retired from working in a profession libérale (self-employed profession). I had paid into French social security caisses, but not enough to build up much pension, and I receive the ASPA pension top-up benefit and French healthcare. If I need to supplement income with becoming an auto-entrepreneur will I need to pay all of the social contributions again? M.W.