Hi Reza,
There are several different ways to upgrade the clients. This KB discusses RU2, but would also apply for RU2 MP1.
Best practices for upgrading to Symantec Endpoint Protection 12.1.2
http://www.symantec.com/docs/TECH163700
If your clients are managed, I'd go for auto-upgrade: that's always worked well for my own clients.
With thanks and best regards,
Mick