i painted my entire basement walls that were a dark brown panel. I filled the joints with drywall mud (it really does not take as long as you would think) and then gave it a coat of KILZ to seal it - It has not cracked in almost three years the easiest would be do re-seal and paint again - I tried caulking and it made a mess - it is very dificult to get level - I did caulk around the baseboard and top molding. I would use an electric sander to smooth the old filler - re-apply filler -seal with KILZ and paint