Please don't despair, it sounds like you've got the dose almost right! Based on the fact that the novomix is also sending her low it might be better to change back to basal/ bolus and try levemir giving half a unit. if you reduce novomix at tea time her bg will then be much higher before bed and although she may then wake with a good reading, she will have been high for the majority of the night. Going to bed between 8 & 10 are good readings and i wouldn't of thought it is advisable to send her up any higher than this. You may even find that if you did go back to basal / bolus, she may not need any background insulin at all. It does sound like she is producing a lot of her own insulin so if she goes to bed around 8 you may find her own insulin is enough to keep her stable, although again this will involve some nightime testing!
I know it doesn't help you ,but we have spent the last 4 months trying to adjust my son's basal. it has been very hard to get the dose right and once we think we've got there, his requirement changes! We are trying to get pumps at the moment as this helps to get the control tighter.
Once you get the dose and time right then things will get easier. It is still always good to do random tests in the night as it can be a real eye-opener! A child doesn't necessarily wake up in the night If the sugar goes low, they can sleep through and in the morning wake up with very high blood sugar, or even ok as the slow acting insulin has then brought their bg down again.
