Hi Ajit,
The version of Tomcat is updated periodically. SEP 12.1 RU3 has Tomcat 7.0.33 built in to it.
A warning: please do no try to manually update the Tomcat component built into the SEPM. The Tomcat that ships with SEPM is integrated tightly with Symantec software and tuned to work well and securely with it. Making changes to Tomcat binaries, libraries, components etc will likely cause the SEPM to fail or become less secure- it will certainly be unsupported, because you will be operating with a combiantion that has not been tested.
Please do update this thread with news if there is a partciluar reason why the version of Tomcat in use is important....
Hope this helps!
Mick