You need to redirect her every single time, EVERY time that she tries to bite you on the face.
Distract her, give her your fingers to "nibble" on instead.
God forbid she become startled while nibbling on your face - that could cause a SERIOUS injury before you have time to even register what is happening.
Next time she starts to nibble at your face, move her AWAY from your face, do not continue to allow it to happen.
Tell her to "kiss" your fingers instead, and offer her the back of a finger, keeping your finger slightly curled into your hand.
My Ginger was a face licker - she tried to sandpaper my nose off almost every night when she was a kitten.
Today, she knows to wait until I wake up, then she gets on my lap and gives my fingers a wash - I get daily kisses from her this way now, and my poor face is spared.
Give redirection a try and let us know how it goes!