Nina, either that "lunging" move has scared her or she'll think you're playing a game, so I'd stop that right away unless you do want it to become a game. When Renji and I wrestle, he does mouth and we do play rough but that's the only time he can mouth and if he gets too rough, I yelp, give him a "how dare you, that hurt" look, and walk away. I rarely have to do that because if he wants the game to continue, he must mind himself. I also toss in obedience; if I see him getting too rough, yelling "no no no" is just going to make me sound like a whiny puppy. I tell him to "down" and then we redirect into an indoor game of fetch. How much physical exercise and MENTAL exercise (training) is your dog getting per day? We can spend an hour of hard fetch and training at the park each day and my dog will still pester us in the evening, pushing toys in our laps, so some dogs really do need a lot of energy-busting.
Anyway, make sure she gets more than enough exercise. Whatever she is getting now, triple it. Then if she starts mouthing, IGNORE HER. If you were petting her and she starts to mouth, then dorp everything and pretend she no longer exists, that she's no more than a fiber on your carpet. She might continue to pester you, but remember that she's used to bugging you for a response. At one point, she is going to give up and walk away, wondering why you don't think she exists. Continue to ignore her, then at YOUR will, call her over to do some fun obedience. If the mouthing resumes, repeat. Dogs HATE being ignored, that's one thing they learn quickly from, so if you no longer acknowledge her existence when she starts to mouth, that behavior should stop fairly quickly. Just make sure she's getting TONS of exercise, the mental exercise being most important!
DnP's advice is also very good! Keep lots of appropriate chew toys around! I notice that when Renji is feeling mouthy, he'll take the initiative and stuff a kong in his mouth before returning to play rough with us.
It saves us from a good chew!