Find out what is important to her and take that away from her for awhile and have her earn it back. If it gets bad and we all know that 14 year olds value their privacy, take her door off the hinges. That would be extreme but if nothing else work. I would still take away her phone and ipod and any other media device. Trust me all that combined, that would bother a 14 year old.
My daughter got like that quite a bit but during this one time, it was really bad. It just happened to be around the time she wouldn't get up in time for school quite a bit. I would literally have to go in 20 times to get her up. She was 16-17 at the time. Definitely old enough to get herself up. So one day she got up late again and I refused to take her to school. So I told her since she wanted a day off, she was going to do some work here at the house. I had her mow the acre lot we live on, scrub the tile grout with a toothbrush, wash all the baseboards, do the floors, dishes and oh some laundry. Wouldn't you know, she started getting up on time and her mouthing stopped. Of course the mouthing started up again later on but that's expected. Sometimes, us moms have to get creative. Good luck!