Does she have to go to a full day program? I know there are lots of half day programs out there. Some kids just need more sleep and it may benefit her more to be getting the extra sleep as opposed to the schooling at her age. If it has to be full day, then I would keep doing what you are doing and moving bedtime earlier and earlier. It is a tough task to do this time of year though when it is still light out and the kids can hear other kids out playing.
I read the book Healthy Sleep Habits, Happy Child a while back. While most of the book pertains to infants and toddlers, there is a section for pre-schoolers and older children. It may be worth borrowing from the library just to give that section a quick read. I understand the sleep issue though. My daughter goes to a special ed pre-school program in the afternoons so she misses out on that down-time. She makes up for it at night but I rarely see her rise in the mornings before 9-9:30. She is just too tired for the day when we have to get her up earlier. I have a feeling switching to all day kindergarten is going to be really rough because she will be losing that extra 2-2.5hours rest she is used to having.