Take her phone away until she is at school. Take it at night and charge it for her... maybe she is staying up all night texting etc?

Have her set her clothes and things out the night before. Restrict any other activities until she does what she is required to do.

I know some may think this too harsh, as she's depressed already. You'd be amazed at how good she will begin to feel as she does the things she knows she should do--and you praise her for it. It will begin the upward spiral. Arguing won't work...she needs discipline and now. Children crave discipline...rules and guidelines so they know where they stand....

...and like another mentioned, if she doesn't learn this NOW with YOU the hard way... she may never learn it...and it's a cruel world out where she's going...

Yes, she needs to learn how to cope and how to push through even when she doesn't feel like it...if she won't learn that from you, maybe she'll listen to someone outside the family.