Yes, you can rebook it online using the "change reservation" function. It will allow you to choose which leg of your flights you want to change. You can do this multiple times without penalty if the price changes again. HOWEVER, you will NOT be getting an actual refund to your credit card. They will hold that dollar amount as a credit for you to use on a future flight. I think it has to be used within 18 months. If you booked with SWA Rapid Reward points, your points will go back to your points account with no expiration. Also, the refunded credits will be tied to each individual person in your party. I don't know how this works for families with minors flying, if parents can use those credits for themselves later or not.