You need to upgrade PAM Proxy and you want to preserve the proxy id as it is used in thousands of the accounts.
All versions
Only way to upgrade the Windows proxy is to uninstall the existing proxy and install the new version. See techdoc : 232880
Uninstalling old version of Windows Proxy. Installing new version of Windows Proxy for PAM upgrade
As long as the corresponding proxy instance from PAM is not deleted the same record will be updated and everything should work as it is.