10.1 comes with 0.9.12, which is the latest developmental version...so there is nothing to upgrade to...you've got the latest already
for upgrading, i use slackpkg which comes with 10.1, on the 3rd disk under extras...or you can download it from slackware.com
i used it this week to bring my 10.1 up to current.
there's a few others like swaret and slapt-get, i've never used those so i can't say how well they work. you can also find tons of packages for slack at linuxpackages