First, if you feel like the daycare is no longer a good fit for your daughter, I would look into other places. Make a list and weigh the pros and cons of moving her. She has been at this place since infancy, so is moving her at this point worse than the classroom issue? Are there even other preschool options where you will get what you are looking for so you don't move her and run into the same issue? Ect.
Now, as for the classroom/age issue, I do think you are over thinking it all. Play is a huge part of learning and she is a very young 3 at this point, so I would see how this year goes and take it from there. She will be four next year and in the older classroom, so she will get to experience before she leaves the daycare, just not this year. (as for being with the same kids...kids come and go in daycares and schools, so trust me, you will meet more of her classmates than you will know what to do with as she gets older
)
The cool thing is, your daughter will get the amazing opportunity to be the oldest in her class (a leader), as well as the youngest in her kindergarten class. She gets to experience what it is like to be both and that is great! Another option, if she gets close to kindergarten and you feel she is not ready (she will be a very young 5), don't send her. I didn't send mine till 6, but every kid is different, so just don't rush it and keep that option in mind.
The academic thing is so over rated and I actually think it might be a great thing for your daughter to stay in the younger group. They will probably use a more play based method of learning and I bet she will excel at it and have way more fun. She gets to play and be a kid for another year! The 3 year old learning level includes mostly just play time. That is how they learn. I just feel like some parents put too much emphasis on the academics and not enough on play, self help skills, manners, sleep and eating habits, ect.