Hi,
I just sent the email link to your email address. Please use that link to download the most recent version of SportMart.
With VM2.x -> VM3.x and J2.5 -> J3.4 many things have changed. So upgrading/migrating will be pain in the ass (not because of our template SportMart but because of the nature of Joomla)... SportMart doesn't have any manual for upgrading specifically. Because there is nothing special about SportMart upgrading. You should follow the same procedure that you do for upgrading an ordinary VM+Joomla system. Use google.com for more info about this topic.. But again i must say, upgrading/migrating is very very hard process and tent to cause bugs/problems. It is not stable... It is always better to follow the QuickStart method and start everything from scratch, then use copy-paste to carry the old contents from the old-website.
FYI: You free update subsection will expire on January 1st , 2016
Regards.