Most cereals are full of carbs and these will put up Bg levels, so you really are going to have to find alternatives as Sue said.
My own two kids were nightmares to feed as all they ever wanted was a bowl of cereal for supper, breakfast and even with an evening meal. They finally started eating savoury stuff which made life a little easier, but neither of them were Diabetic ?
I don't eat before bedtime unless my Bg level is really low ? Even then it might just be a cracker and some cheese, nothing much. Kid's want to eat all the time. My breakfast can be like what Hana has stated, or a traditional Bacon & Egg plus mushrooms or tom's but your daughter would probably feel sick at the thought. I have fruit as well for breakfast, apples, cheese, cold meats etc. Does your daughter like these foods ?
It has to be a joint thing by working out what she likes and gently persuading her to eat more healthy options.