Absolutely don't stop.

There's no way you're stopping now. This spell's fun is only beginning. Your hands remove from her chest, giving her a window of hope before you bring your face down against her plush breasts. Your mouth begins to tease her now instead, licking your tongue around and around each nipple, stopping only to offer a brief suck of the tips.

With each movement of your mouth, she yelps, and her legs begin to move more sporadically. It seems as if she's going to nearly cum from the teasing itself, though you know that because of the spell, that's actually impossible. Like you thought before, the fun of the spell has only begun.

"F-..." she nearly curses, but lets out a short yelp. "S-Stop! I can't take it any m-more!"