Can joints that have been under filled with sealant be “topped off” with additional sealant after they have cured?

Chemical-cured sealants such as Deck-O-Seal products, Pourthane, C/A Sof-Seal, do not adhere well to themselves unless solvent wiped and/or abraded prior to reapplication. 3405 Safe-Seal has poor adhesion to itself initially but will improve after it totally cures within several weeks. Hot applied sealants will remelt at the surface and good adhesion can be obtained.