Let it ride.
Yeast are working on their schedule and not ours as brewers.
I've had krausens last for almost 3 weeks. Had to rouse yeast and gotten a second smaller krausen.
What temp is your fermenter? If it's lower end for the yeast strain, it could be working for a while. Hotter ferments tend to have shorter yeast lifecycles, and therefore shorter krausen duration.
If the yeast are still working, you have nothing to worry about.