I've collected swarms and get calls from the homeowner/resident days later that there are still remaining bees where I collected the swarm from. My experience is once they've decided to leave, they don't go back.
Try baiting up, moving up 1-2 frames of brood from the bottom up to the second box. That'll draw up the nurse bees into the new box and maybe speed up the queen's access for room to lay. Once they've filled up the brood area with honey they may have made up their mind to swarm so check back for queen cells that you might want to remove for growing out elsewhere. Just leave them one or two in case the queen has already left.
http://www.bushfarms.com/beesswarmcontrol.htm#opening