You should configure the software to update itself automatically on a daily basis, or at the very least, run , open the Applications folder on your hard drive, then double-click Symantec Solutions.
Double-click Live Update, then Update Everything Now.
Or you can click on the Symantec icon on the top Menu bar, and select Live Update from the pull-down menu. When it is done downloading the latest information, you should restart your computer.
Make sure you review the benefits of upgrading to the latest version of SEP 12.1.x, and check out Symantec’s Help diagnostic tool to determine if your system meets the minimum requirements.
There are a lot of moving parts to admin work, so here is a list of Symantec’s guides to content revision configuration, server certificate updates, GPO, testing authentication, central deployment, Live Update, and clients with both SEP and Data Loss Prevention: If your users do not use a VPN, you should change the Live Update policy setting to use the default Symantec Live Update server – this allows remote clients to update any time they connect to the Internet.
The article covers things like ensuring all SEP clients and SEPMS are running the latest maintenance release, using the Group Update Provider (GUP) for content distribution, and how to ensure out-of-date SEP clients to still get incremental updates.
It even explains the best way to use a MS-SQL database for large environments.
According to Symantec, an upgrade to version 12.1.5 will take much longer than you expect (sorry).