First, don't use alcohol or ammonia on plexi, it causes damage i.e., crazing, cloudiness, cracking, etc. Windex has alcohol in it.
This may or may not be the problem or a contributing factor.
Also, depending on what is used to wipe with, there could be micro scratches.
The best way to remove the damage, is to do a progressive polishing process. This will require a buff motor and the appropriate materials. There is no reason for a buff jack (industrial buffer), any motor that can spin 1750 rpm is adequate.
The first step is to do something taboo... you will sand the surface. That's where the progressive process comes into effect.
If you would like the complete process, contact me, and I'll list the process. Remember, it will require a buff motor. HF has one that will do the job without effort.
Yes, it is necessary to start at the beginning, with the sanding. Buffing alone, will not remove the crazing. It could disguise it temporarily, but it will reappear. Sanding removes the damaged surface.