It used to be that hitting the refresh arrow/loop button in preferences -> account would pull down a new provisioning profile with all ur new devices.
Now it just do
I also couldn't find a way to delete or refresh the provisioning profile in Xcode.
I managed to pull the provisioning profile with the new devices by quitting Xcode, deleting the Development provisioning profiles - the ones marked "Active (Managed by Xcode)" - on the Apple Developer site, then reopening Xcode and choosing the team in General settings for the app target. Xcode recreated the profiles (as confirmed on the developer site) and the device was included.