If the spectrum environment has been migrated to new hardware what is the correct process for updating the data source in CAPC performance center?
Any version of CAPM
If a new instance of Spectrum is installed and you want to replace the existing Spectrum data source in CAPC then the data source in CAPC should be deleted. Then you should wait for global sync to complete, then add the new Spectrum data source. It will create a new IP domain global collection in the new Spectrum instance, where you can add devices, which will then sync to CAPC and after discovery, consolidate to existing DA / NFA devices.
If the devices in question are only coming from Spectrum, they will be removed from the inventory entirely. As long as the device is discovered in the "Monitored Items Management > Monitored Devices" view it will continue to collect data without issue