agree. replace it if it's available. Otherwise, they clean up and resurface pretty well -- same as what you would do with a head cover (hard surface and some wet/dry sandpaper.)
If it is easily replaceable, and the cost isn't over the top, buy a new one. If you can't find a direct replacement, then you can clean that one up and sand the issues a little and reuse it. But I would replace if I could first. JMHO