I got a screwed up save. I was using a custom race and became a high lvl Vampire Lord. BY then everything worked fine

Now, that I ahd to reinstlal SKyrim whenever I want to revert the Vampire Lord form with that save he transforms into a naked Vl instead of back in the human form. I guess thats because the game can't find the custom race anymore.
So I guess that some quest tells the save what race the VL needs to revert to (which is corrupted now). So I would like to reset that quest somehow so that a working race gets tied to the save. (If that is the way it works ^^) Any idea what quest it might be?