I'm unsure what you're asking.
If you're still in Mercenary difficulty (and wow, that's impressive at level 60), you can restart on the harder difficulty Veteran while keeping your old party by clicking "Single Player" in the main menu, selecting your party out of those available, then hitting next, then selecting the Veteran difficulty (should be the middle of three choices).
If you're wondering about a completely different map, sorry, there's only one (and a smaller one is added with the expansion pack Broken World). You can replay in Veteran and Elite, but it will be the same map.
There's always a possibility someone will create a new map to play on, but I haven't heard of anyone doing that yet.