Had you inspected the hive previously since you hived the swarm? Is there pollen and/or nectar stored? How many frames are drawn? Are there a lot of bees, or just a handful? If they're low on nectar/honey, you should feed. If they're packed, it's possible you're honey bound and there's no room for the queen to lay. If all the frames are drawn, and they have sufficient stores, you should add a second hive body. Requeening will be fine, assuming you are actually queenless (ie, the hive is not honey bound and the queen has a place to lay, if there were one there).