I currently have a ressie for CRT at 3:20pm. I'm looking for a later time. If when I'm in Disney a ressie pops up for a later time, how do I go about switching the res. without double paying??
You don't...you would have to cancel the previous reservation. You can do that after you have booked the new one to make sure you get the new one. You would be refunded for the old one (assuming it is not within the cancellation window).
We did this in December when looking for a better CRT breakfast ADR for our January trip. It all worked out fine - we did just as TDCNala suggested - booked and payed for the new ADR, then cancelled the old one and received the refund.