Correct - just log into your flight, hit change and then pick either a new flight or the same. Assuming you originally purchased a Wanna Get Away fair the difference will be held as a credit for the passenger to use in the future. NOTE: only the passenger can use the credit for that particular ticket and KEEP this confirmation number in a safe place - when it comes time to use that credit you will need the confirmation number.
4 days in a row my Feb 14th flight dropped - I was able to rebook all 4 days for the lower rate. I paid in points - so my points just went back into my account. Love SWA for this!!!