stopping contract?

i know there are rules against this but im interested how it works.

my 2 year plan just ran out..and i have an option to upgrade phone....but it would be hella of a lot cheaper to get a phone with a new 2 year contract instead of an upgrade...i cant stop my plan right now since my 2 year is up anyways and then sigh back up again right? theres no way around this?

just wondering:-)

thanks