Is there any kind of Newgame+ or similar for replay value?
First of all, there's naturally the different difficulty levels. Some things in the game will also be different in a new game, regardless of the difficulty level, like the location of some of the objects/ingredients that you can find, as well as the chitchat of some of the NPCs.
But what's more important for replay value, is the powerful editor and the one-click mod sharing system. We're very happy that Driftmoon already comes with a number of mods, even though the game is only just about to be released. :)