It's in Debian (possibly upstream only), but you can download the latest version from their website and install it manually.
The MX 15/ MEPIS repositories
: Backports galore! If we don't have something, just ask and we'll try--we like challenges. New packages: Variety 0.6.2, Pale Moon 27.0.1, Liquorix kernel 4.8-16, SMPlayer 16.11.0, Corebird 1.0,Shotwell 24.2, Mesa 13