I just got a new cell phone and there is no easy way to transfer my authenticator key from the old phone to the new one. The easiest way for me to deal with this will be to turn off 2-factor authentication, then re-enable it using my new phone.
Just a hint (too late for you now)... When you set up two factor using authenticator, do a screen cap of the QR Code and save to an encrypted folder on your system. Then any time you need to set up a new device, you can use the same QR Code and it will work. You can also set up multiple simultaneous authenticators this way.