I have the same problem from time to time because we don't have that many maps, except you practice on yours a lot more than me, so you probably know then extremely well!
Anyways, when you start to become board and too confident it's often because you're just relaxing in your comfort level. If you'd like more of a challenge, try to pick up the speed to the point where it's hard to think, even if you were to just be running. This is a great way to gain the experience for what it feels like when you're running in high level races, if you need something to watch/think about, then focus on how quickly you can move along the map at top speed, and picture what that would be like on a completely foreign map.
Maybe you should do some map reading(of foreign, possibly swiss maps ;P) before orienteering to get you thinking and in the right mindset.
Orienteering is a sport about mastering your focus even when you don't have it
But it sounds like you've been improving a lot, keep up the good work!
Yeah thanks! I'll try it out next time on a familiar map, and I've kept meaning to look at some swiss maps but never got around to it.