Sorry, once vinyl has lost it's flexibility due to UV degradation (the plasticizers that make it flexible are destroyed) there's no way to bring it back. Some spot repairs or patches can be done with variable results, these processes add new material over the brittle areas but usually the repair is at least partially visible. Go to a local area restraunt with vinyl seats in the booths like a Denny's and ask the manager who they use to do repairs, those guys are usually pretty good.

Best bet is to remove the pad and have Just Dashes re-skin it.