At that she is use bribery.
Key is finding the right bribe and making it her decision to do this, not yours.
The prize needs to be something that she really, really, REALLY wants. Sit her in front of the Argos catalogue with (say) and £20 budget and ask her what she wants.
Agree she can have the present if she can manage 7 night's sleeping all night in her bed. But not until she's ready.
Have craft stuff prepared. Ask her to help you make a 7 day chart. Take her out to choose some amazing stickers - get choice.
But all the time keep on reiterating that this doesn't need to be for now. That you are getting ready for when she wants to earn her [insert amazing present].
Get ready. Make the chart. Put it up. Then ask the question - are you ready to earn the amazing present and sleep all night? Shall we do this!?
If its a yes, big-up her decision. Empower her with her own choice. This isnt you making her,this is her choice.
Massive big praise of she manages it in the morning. Treat it like something amazing - have het phone grandparents with this amazing achievment for example.
If she shows up at your bedside in the night, give her a redeeming chance. You need to be alert enough to catch her when she enters your room and engage with her staight away: Do you still want the [amazing present]? Remember you need to stay in your bed all night to get it. It's ok if you decide you can't manage and want to stay with me. But it will mean you will not get the [amazing present]. Why don't you try? Shall I take you back so you can have the [amazing present]?
Make it her decision, not yours.