While Awlgrip says you should not polish or repair Awlgrip, plenty of people in the marine industry do just that. It is tricky to repair and have it look good, but can be done. They also make Awlcraft, a different PU paint that can be polished and repaired. There are a number of competing products in the car/boat/aircraft paint business that are also 2 part PU paints and are very durable compared to gel coat. If you spray any of these, make sure you have a good respirator, the fumes can kill you.
After 6 years, the Awlgrip on my sailboat looks like new, and is often mistaken for new.