Hi, your lo must be very 'with-it 'and astute - we moved house when my ds2 was 3yrs and he wasn't phased at all, just went with the flow lol!
I would do whatever you can to hide anything stressful about the move from her, and make it all happy - an adventure. Explain that she will go to a nicer preschool and make lots of lovely new friends. Tell her about all the nice things you will be able to do once you have moved house.
Has she seen her new house/bedroom yet? Can you let her choose some new things for her room or if you are going to decorate she can shoose colours?
If you can afford to, get her a new toy or something she really wants as a moving present ?
And just make sure her new preschool is a nice one, and they give her plenty of settling in sessions etc.
Good luck - moving is stressful lol! xx