It's probably a good idea to pause it lest you get failures or alerts that say it can't connect to vCenter. Prior to doing any upgrades, on your part you want to validate very carefully that the target version to which you're wanting to upgrade your vCenter is supported by your replication software. Do not assume; check and validate with your software vendor. You may require a minor update or even a full version upgrade. Being smart about how you do upgrades is important to ensure you have only minimal disruptions to your replicas.