Nikon D5100 Sleep Mode?

I have a Nikon D5100 and I've tried setting it up for silly little photobooths at parties with a remote and it's been a hit, but after a while of inactivity the camera goes into sleep mode and the remote is then shut off so then I have to go reset it up for the remote.

Is there anyway to keep it connected to the remote or even a way to turn off the sleep mode? I have another party tomorrow and was hoping to get this settled so I don't have to worry about it.

R.T.F.M!
Look for the Menu for Auto Off Timers.

If you look in your user manual, you will see that you can turn off the "sleep" mode, but in doing so, you will soon deplete the battery.

For what you want to do, you will need an AC power adapter so you can connect the camera to the mains and bypass the battery all together.

See page 161 in your manual, C4: Remote on Duration.