Hello,
I would recommend a check on this Thread with similar Issue:
https://www-secure.symantec.com/connect/forums/move-sepm-another-server-0
However, to answer your question:
Yes, you can use the SylinkReplacer version_12.1 for getting all the clients back.
To get that tool you will have to call symantec or log a web case.
QuickStart Guide - Create and Manage Support Cases in SymWISE
http://www.symantec.com/docs/HOWTO31132
How to update a support case and upload diagnostic files with MySupport
http://www.symantec.com/docs/TECH71023
OR
Regional Support Telephone Numbers:
United States: https://support.broadcom.com (407-357-7600 from outside the United States)
Australia: 1300 365510 (+61 2 8220 7111 from outside Australia)
United Kingdom: +44 (0) 870 606 6000
Additional contact numbers: http://www.symantec.com/business/support/contact_techsupp_static.jsp
Hope that helps!!