If you’re getting a new iPhone in the near future, here’s our Sweet Setup article from a few months ago with the steps on how to pair your Apple Watch to your new phone. In short, back up your old iPhone, un-pair your Watch, set up your new iPhone and restore from the iCloud backup, then pair your Watch to the new phone, and chose to restore the Watch from backup.
And, speaking of iPhone upgrades, in case you need some tips with how to backup your current device before setting up your new one, we’ve got you covered.