Repetition has to be one of the major problems in Classical music, perhaps most especially in Schubert. Many performers solve the problem by simply playing everything fast and faster.
There has to be more going on than is apparent at first hearing.
A great trick, shared by Schubert and Dvorak, is to undo the tyranny of the four-beat bar and of the four-bar phrase. On the surface much of their music conforms to the expected but on closer look it doesn't at all. Articulations are clear, ambiguities abound, resolutions rarely truly resolve--what had seemed to be balanced turns out to be the opposite.
This can never get dull because it is precarious every single time.
