I've developed a sort of clear plastic care ritual after years of owning Brit convertibles and aircraft. Piper windshields are expensive...
The key is getting the window absolutely clean before you start as any grit will only make matters worse. Use lots of water and mild compatible soap to clean the windows.
If it is clouded, you need to start w/ a cleaner like Meguires to restore clarity, then polish/protect with either their polish or something like 210 aircraft canopy polish. I prefer the 210, it cleans well and leaves a good protective coating. Once you remove the clouding, use the wash and 210 combo whenever needed.
'85 90 2.5NA
'72 SIII 88"
Couple other cars