I restored my headlights (on a couple of passats) with wet & dry sandpaper and polish. I first tried the toothpaste method and all that, and they worked to a degree, but just get some 800, 1500, 2500 grit w&d sandpaper, making sure to keep the lights wet when doing it, starting on the roughest, and finishing with the lightest. Then polish the living heck out of them. Then seal them right up, preferably with some UV sealant if you can, but if not, then just regular car sealant will do.
After this, they MAY need done every 12-18 months or so, but it's cheap to do, and not too difficult.
For reference, mine went from this:
To this:
Assuming that's what your problem is of course.
On the other hand, can't beat OEM xenons...