Unfortunately, openHistorian 2.0 relies heavily on the configuration database to manage its metadata. There is an autoincrementing integer associated with each measurement which is used as part of the key for the corresponding measurements in the historian database. By deleting the device, you delete all the metadata for that device including its original measurement IDs, and there is no way to get these back without a backup of the configuration. When you recreate the device, it creates all-new data points based on the configuration it receives via the synchrophasor protocol. This creates brand new IDs that are not linked to the original data, and there’s no way to reassociate them since the original IDs were lost when you deleted the device in the first place.
Note that there is a folder called ConfigurationCache in the openHistorian directory that maintains five consecutive backups every time the system reloads configuration. If you’ve already deleted a device and need a copy of those IDs, you should be able to find them there, assuming you haven’t reloaded configuration five times since then.