Southwest ticketing on awards is electronic, and there's no cost in changing, cancelling, or even not showing up for the flight. However, in Southwest's case, you're issued the award (which you have one year to use) automatically when you earn a 16.0 credits (Southwest uses segment-based credits rather than miles), so there's no "redepositing", it's just that you have your award for one year until you actually use it, and can make and change and cancel bookings using that award however many times you want during that year. (Similarly, Southwest PAID tickets, even "nonrefundable" ones, have their funds reusable toward other tickets if you either cancel beforehand or simply don't show up for a flight.)