The Pack-a-Punch Machine returns in Black Ops II, being available in TranZit, and on three of the four Survival maps. On TranZit, the machine needs to be built and the power turned on before you're able to use it. On the other maps (Nuketown Zombies and Town), however, there is no need to go out of your way to have the machine spawn (other than just killing zombies on Nuketown).
It costs 5000 points to upgrade a weapon using the Pack-a-Punch machine, but not all weapons can be upgraded. If it was a weapon that you got off the wall, you can refill its ammo for 4500 points. Some upgraded weapons can be put in the Pack-a-Punch machine again for 2000 points, which will give it an additional attachment; this can be done additional times.
