Hi,
Found this thread
https://www-secure.symantec.com/connect/forums/adding-latest-definition-files-existing-sep-121-ru1-client-package
If using SEP 12.1 version then while exporting package it will contain latest definitions.
But if using SEP 11 version then while exporting package thorugh SEPM it would contain old definitions.
You can refer this artilcle if using SEP 11
How to deploy the Symantec Endpoint Protection (SEP) client Release Update 5 or newer with current virus definitions and intrusion prevention signatures.
http://www.symantec.com/docs/TECH104779
This issue is addressed in SEP 12.1