Is the hair spell that Rochelle put on Laura permanent?

I've been thinking the same thing but I think once Sarah took her power from her, the spell was broken. Plus Rachel was the only one who showed any sort of remorse for what she was caused.

It was a spell. What did Lirio say to Sarah in her shop? About Sarah's love spell against Chris? Sarah wanted to stop it because she could see that things had gone too far (Chris was practically stalking her and eventually tried to rape her). Lirio said something along the lines of 'when you open a floodgate, how do you stop it? (meaning the flood waters). You can't. And as Lirio said to Sarah, the spell 'would have to run it's course'.

Rochelle's spell then, like Sarah's, would have to run it's course. And then, only then, would the spell be broken. With Chris it was too late since Sarah murdered him. In the world within "The Craft" one can assume that, eventually, Rochelle's spell was broken - particularly when she lost her powers - and Laura's hair would grow back.

There's nothing to indicate it will wear off or stop or progress worse. Once you open the flood gates... I think this is the point of messing around with witchcraft and spells. Laura's spell was concerning her being a racist, it could have kept progressing into unsightly skin pigmentation, her and her family eventually being 'outcast' or anything at all really. Hypothetically, i'd assume the power of the spells in their initial casting would be dependent on how much power they had within them at that point.