This is basically the same issue as our cladding. Once the hazing starts, you CAN bring the gloss and clarity back, but it will be temporary.

After a few months, depending on your area/climate, you'll be attacking it again.

One permanent solution, is to have them professionally clearcoated. They will then be wet sanded and buffed to a glass-like appearance. Plus, while you're at it, you could choose to slightly tint them (any color) for a custom appearance.

Since the new coating has the UV protection we all need, you won't have to worry about them hazing up for years...