its very easy, you dont have to cancel, just modify. Go to Southwest.com and on the front page, there is a tab that says change flight. you will need your confirmation number. Then select the flight you want and you will receive credit. Its much easier to keep your reservation number. I have changed my flights each time the prices dropped, I started out at $299 for our flight home from MCO to Hartford, and over the past few months the price dropped to $74. I dont think its going to get any lower but I still check everyday LOL!