I found a number of swarm cells in my 3-year survivor hive yesterday (it's swarmed at least once each year since I captured it as a swarm 3 years ago).
I've made a lot of mistakes upon discovering swarm cells in the past, so this time I sat down on a stump and reminded myself that swarm cells aren't a sign that I'm a rotten beekeeper...swarm cells are often simply the sign of a vigorous and reproductive hive. And then I decided on the following course of action:
Set up a new hive next to the hive that's preparing to swarm.
Examine each frame in the original hive until I find the old queen and put her in the new hive box.
Leave all the swarm cells in the original hive.
Add to the new box several frames of larva, brood, and all the bees on those frames.
Add to the new box a frame with lots of nectar or honey
Close up the new hive.
Move both hives equidistant from and with their entrances facing the location of the original hive (so returning foragers have to choose one hive or the other when confronted with an empty space at their old hive location).
Leave.
I did make one decision that I question (though I think I'd do it again in the same situation): I didn't have a queen catcher with me, so when I spotted the old queen, I simply removed the entire frame on which I found her and placed it in the new hive. HOWEVER, there was also one small swarm cell on that frame, so I cut it out with my hive tool. Bad? I didn't want to move a swarm cell into the new hive with the old queen.
-Liz