Since getting a replacement front windscreen, I
haven't been able to get water to bead on it.
Water just spreads out evenly, making vision difficult. I've tried Jif, dishwashing liquid, soap, Autosol, petrol, etc., but to no avail.
A lot depends on what caused the condition, and if
it is from the wrapping plastic, either petrol or kerosene would clean it off. If that does not work, you will
have to start experimenting with different solvents.
Try paint thinner as that usually takes off most paint-based films. Do not use Autosol
or any abrasive cleaners, as they will leave scratches on the glass.