Hey, I think XP is one of the easiest and best things to hack to get a different feel from your game.
XP is the best way to say to your players “this is what I want you to do”. The default assumption of Mausritter is that the players are poor and desperate mouse adventurers, without a permanent home base or social structure to rely on. They get XP for doing the dangerous things that other mice won’t (and they get XP for re-investing it into the communities that previously shunned them).
One option that’s not in the rulebook (and probably should be) is that I also award XP to my players for rewards given by other mice. So if the village puts together a collection of 300 pips to reward the mice from rescuing their matriarch from an owl, that would count as 300 pips for XP purposes too.
For an exploration-focused campaign, you could easily have non-player mice who are willing to pay rewards for mapped locations, or strange new discoveries. Or if you want to reward exploration directly, I would write out a list of things you want to reward players for, then assign values to them. Make this public, so players know what they’re aiming for ie. Mapping hex: 100xp; Mapping adventure site: 1000xp; Discovering a new settlement: 250xp; Finding a new spell: 100px.
For a Mouseguard-type setting, where mice are part of an hierarchical organisation and being sent on missions, I would consider getting rid of XP entirely and looking at what Into the Odd (on what a lot of Mausritter is based on) does. In that, you advance to level 2 after surviving your first mission, level 3 once you’ve completed three more after that, level 4 after five more, and taking on an apprentice, etc.