Can't reset Circle

I've recently installed the Circle app for a RBK53 Orbi network. Unfortunately one of the kids has subsequently removed the app from my phone (don't ask...). I reinstalled the app & tried the join the existing Circle. I've no idea what the circle passcode is so I tried the "I'm the only Circle admin" link. I clicked the "Send Passcode" option but didn't receive a text. I'm guessing that I mistyped the phone number when I originally set this up. Any ideas to to resolve this (ideally without resetting the router back to factory default)?

Cheers

Mark