Mandi, I fly regularly, and have run into this situation several times on several airlines. As the new flights assigned to you won't work, you can call the airline and have them changed to another time without additional charge to you.
Same thing happened to us on Delta last year. We ended up flying home from FLL at ~5:00 pm (on a non-stop) after a cruise rather than our originally scheduled early pm flight (one stop). The flight we ended up with was actually much more expensive than what we had booked, but we didn't have to pay the difference.
Let us know how it turns out.