D.B.
I have written notes for my kids saying that they overslept (we all overslept). Then I let the school decide if it's an excused tardy or not. (It seems that it's always an unexcused tardy.) It cost my son not being able to redo a paper for a better grade. I felt bad that I didn't set the alarm.
But I don't ever use an excuse - not when it's not an excuse.
Is she college-bound? Find something that will speak to her to help her see that she won't get in college if she keeps it up. If she doesn't want to go to college, try to get her to see the difference in wages paid to those who don't graduate from high school versus those who do.
So sorry,
Dawn