You MIGHT be able to clear faded headlights using toothpaste but I promise you the problem is going to return in weeks if you succeed. You must replace the missing UV inhibitor to prevent the fade from returning. When I restore headlights, I sand and polish to a 3500 grit level, (yes, 3500 grit) and then wipe on a mixture of polyurethane gloss spar varnish and mineral spirits. The spar varnish has a great deal of UV inhibitor in it.
Trust me, I’m a professional… Ogden Clear Headlights