Don't get me wrong, you could certainly try a spell. It could easily aid you, and maybe make it grow faster. Having said that, you would still have to actively work to improve your life factors to promote said hair growth, like reducing stress and eating healthily.
I have also heard about an older superstition that if you trip the ends of your hair back just a bit on the full moon, it will grow back faster. The trimming doesn't have to even be very much. Just enough to take the very ends off; maybe a millimeter or two.