Hello,
Autoupgrade would work best for you.
The AutoUpgrade process lets you automatically upgrade the Symantec Endpoint Protection client software for all the clients that are contained in a group.
For example, you can use AutoUpgrade to upgrade clients from the MR2 release to the MR3 release.
You can also add a client installation package by using the client installation files from the product disc. You must test the AutoUpgrade process before you attempt to upgrade a large number of clients in your production network.
If you do not have a test network, you can create a test group. You can add a few non-critical clients to the test group and upgrade them by using AutoUpgrade. You can confirm the upgrade completed successfully by verifying the version number of the client software that appears in the About dialog box.
Check these Symantec Knowledgebase Articles on AutoUpgrade:
Upgrading clients by using AutoUpgrade
How to temporarily stop AutoUpgrade from continuing