You didn't mention what MODE it was using when it no longer worked (or if it included both LP and electric mode). If it doesn't work on either mode it is PROBABLY a loss of refrigerant which is pretty much terminal. Check to be sure the gas flame is burning properly and that the electric element is getting power and it's probably safe to assume that if both of these things are working properly, it's toast. The fact that it lost it ability to cool GRADUALLY is another indication of refrigerant loss.
Good luck / Skip
