Hi Rao
Kindly follow the steps to install & Configure the new Trex instance on Windows 2012
1. On exiting Trex server Take the backup of Indexes by using the 'ExportManager.py" as mention in the SAP Note 975965 - TREX 7.0/7.1: Data backup (online) and recovery
2. Install the new Trex instance in the Windows 2012. http://scn.sap.com/docs/DOC-43539 (This link describes for Linux but it will be useful for windows as well)
3. Trex configurations as per your requirement http://scn.sap.com/docs/DOC-43539 (This link describes for Linux but it will be useful for windows as well)
4. Restore the Trex backup as per the SAP Note 975965 - TREX 7.0/7.1: Data backup (online) and recovery
Thanks & Regards
Ram