Awlgrip and Alumagrip are the same polyester urethane paint with the except that Alumigrip is for aluminum aircraft uses. These paints are very hard and do not buff well at all, unlike Imron which is much softer. Imron doesn't last like Awlgrip though either. If the cleaner doesn't work, it's time for a wet sand and a color coat.
We have a boat with an old Awlgrip job on it (white) that looks pretty sad in the fall and winter but after a wash with Awlwash and hand polishing with Awlcare it does improve significantly. It doesn't quite have that 'wet' look but does look way better!