How do you stop play biting?

My dog is terrier/German shepherd mix and she is a year old. She’s been okay biting for a while but now it is starting to hurt. She means no harm but she’s getting to the point where she might break skin. I lie down and she just jumps and starts biting my hand or tries to go for my face! When I tell her no she just barks at me and doesn’t let up until I leave or play with her. I need this to stop and I am training her myself. Any advice