Best way to upgrade is phone Customer Services. The upgrade site online is very broken
You wouldn't have to resign a new 12 months as you already have both the TV and BB - unless they offer you a free router which will recontract the broadband to 12 months
---------- Post added at 17:52 ---------- Previous post was at 17:50 ----------
Although it may not be worth doing if you don't want the router - you will soon be getting a free upgrade to 10Mbit anyway