You may get replies advocating all sorts of buffing agents and miracle potions which will clear your problem,but having been down that route all of them only provided a temporary fix.
In the end I got a new window fitted by local sail maker at very little cost.
Agree about the replacement - got mine done about 3 years ago and makes a difference.
Whilst its being done ask the sailmaker what spray they recommend for protecting it as I think there are different materials used for windows, different conditions etc. We got a spray that was wiped on and seems to have helped but not really enough wear to know one way or the other.