How to re-pair Versa with FB app on android phone

[Stivat]

My Versa occasionally has trouble syncing to my Android phone, so today I thought I would unpair in in my phone's Bluetooth settings and then re-pair it. But now there doesn't see to be any way to re-pair it as it doesn't show up in the list of Bluetooth devices (it did previously). I know I can go through setup again and set it up as a new device, but this will loose all my previous data which I don't want to do. Any other way around this?
Re. the syncing, it seems to be able to sync automatically at times, but not at other times when I want to do a manual sync. Any ideas about this also? Phone and watch are always close together. 
Thanks

[SunsetRunner]

Un-pairing and re-pairing will NOT cause you to lose a single byte of data. What phone are you using?

[Stivat]

Hi cbwilsha, thanks for your reply. 
Can you advise how to re-pair it?
The only way I can see is to remove the device within the Fitbit app on my phone and then run Setup again. This will remove the data (I've done it before). 
If there is another way to re-pair without having to run Setup again, I would like to know. As I said, it doesn't show up in my phone's list of Bluetooth devices available for pairing. 
My phone is an Oppo R11 running Android 7.1.1
Cheers

[SunsetRunner]

Your phone is not on the Approved Devices list so may work for some functions and not others.