Depends how much the schedule changes. If it's five minutes (or even 20 minutes), probably not. If it's an hour or more or they've change you from a non-stop flight to a connecting flight, you almost certainly would be able to change to a more convenient time or get a refund (not just credits) without any charges. The big issue is that there have to be more convenient flights and there have to be seats available on those flights.
The above applies to most airlines, not just to AirTran.