The badge resale starts Thursday morning, 31 May, at 8:00 a.m. PST.
Once again, you must already have a Member ID and cannot have a four-day or Saturday badge. You can only buy badges for two people.
The resale link is http://www.comic-con.org/cci/
See specific rules and such here. Good luck.
ETA: If you're interested in changing your hotel reservations, you might want to try to do that tonight and tomorrow before a new onslaught of badge-holders tries to book rooms. Downtown hotels are largely sold out but there are plenty of other hotels with vacancies - go on the site and look. You may find a more preferable hotel for one or more nights. Do this now because the first thing people are going to do Thursday after registering is grab a hotel room.