It's in Debian (possibly upstream only), but you can download the latest version from their website and install it manually.
The MEPIS 12 community repository
: more backports than Wheezy-backports!
Totally unofficial! Some packages may also require enabling the Wheezy-backports repository.
New in the main MEPIS 12 repo: xfce4 4.12.1
, Kodi 14.2, and the revamped SMTube.