Recoat
Yes it's not much differnt then refinishing a fishing pole. Well now you are laughing right????? Really, it's basicly finding out whether the manufacture used Polyester resin or Epoxy resin. Then after finding out West Marine or any hardware store or Chandlery should be able to help you with a small can of resin and hardener to go with it . Then it's just a matter of how many coats will it take to bring back the luster. ( Be sure to use a NATURAL bristle brush and not a one with plastic or any other type of imitation bristles) Not sure where you are, but in Calif you can get additives to put in the new resin to be applied which are U V inhibitors. If it's really grungy you might want to take a dampened rag with some actetone to give you a clean surface to which to apply it to. Not too wet though. Acetone is good for clean up as well after the project. Especially if you wish to save the brush.
