The best preventive is the one you can instil within her, herself. But it sounds like THAT one isn't working, so here are some suggestions.
1) We have large wind-chimes which take too many hands to silence, but which 'bong' loudly when either door is opened. They are INSIDE the front door, to one side. You can't manage the door, AND silence the wind chimes.
2) Instal the alarms, but with a SILENT alarm that alerts only in your room. Make sure the security box is also in your room (or at least, an over-ride box). That way you will catch her in the act every time, you will get woken and she won't know why (which slows down her learning of a new way to try to out-fox you).
If you combine both these methods or use another noisemaker, she will take even longer to cotton on to a silent alarm.
And I would put sensor pads in both doors as well as her bedroom window and pressure pad outside her bedroom door. Also with silent alarms.
With the window - you would need to set the sensor so she can open her window far enough to get some air, but no further (not far enough to climb out, for example).
It's fairly easy to do this sort of thing - an Aspie friend of difficult child 3's from a year ago made his own alarm for his bedroom door, with the sound being provided by the chip from a singing birthday card. You could do it with a pressure switch under a mat, or easier still, an invisible light beam.
But if you're going that far, I'd be looking at also installing a hidden camera, transmitting remotely to a recorder in your room. Be careful to not infringe on her privacy (no filming where she regularly gets undressed, for example). This would be much more legal than deadlocking doors.
Marg
oh no....guess I need to check into that!!!!!! And.....yes, a fire hazzard....but we "felt" we had it covered. Suppose not.....not a great idea, but would work for doors & doors only. Windows would come next. 
