Kill him, but keep his robots alive. Walk through the gate and he'll respawn.
Not exactly but this;
Just walk out his door and back in.
You don't have to kill or keep his guardian bots alive -- I believe they have the 24-hour restriction lifted off of the Raid Bosses (as apart of the Hot fix) still in effect. You have to be logged online and into their "server" in order for this to take effect. If you get disconnected you might have to go back to the title screen, log back into XBL then press start to log back into Gearbox's server.