Hi I'm sorry miss understood...
Lavender drops on pillow lavender baths right before school. After her tea try getting her to put her phone down and watch something chilled, even better a book but make sure the big light is turned off and get a cheap lamp- very helpful.
Ideally read a book. Although she is a teenager so maybe a documentary on something she's interested in. Make sure you both have a positive mindset about it. Like could say something like "this lavender stuff is meant to be amazing I've seen reviews of people with chronic sleep deprivation use this and had best sleep in years. Also smells nice as well"
Ask her to try going to sleep about half nine... and say you will wake her up at 9 and you can do something (even just a walk/shop). And say if you had a bad sleep you will just keep coming up every hour and a half.
I think key may be positivity and make her feel like she is actually in control.
Also say you have a feeling all these things together may help.
Make sure maybe tea at 5 send her up for a bath after with lavender, then a documentary in her room with the dim light. Maybe sit with her no giggle convos obvs but just even sit there with her and say my heads hurting can I turn off the lamp?
Then mayve around half eight give her some soup not a lot but a full stomach.
Then after send her up to sleep, keep all lights in the house Dim.
Sorry for how long it was but I feel awful for her.
Hope this helps, I have more tips if this doesn't work xx