The cost of a new sink is not that prohibitive. The life span of the new painting is short term. Unless this sink is some design not made anymore, you may want to consider a permanent replacement. I have seen electro plating, and painting, and they do not last. Doing this for 30 years, I have tested most of the methods and they have short life spans. Since water is one of the most corrosive substances, its real hard on painted (resurfaced) sinks.