It strikes me that there will always be some tension between students having a sense of the near-term relevancy of what they are learning and being pushed beyond the obvious into uncharted waters that may have little or no near-term relevancy. So, there has to be some balance between "bored with where I am" and "bored with where I'm going".
If learning is what happens when we try to make sense of what the world sends our way, the issue of boredom might be addressed, at least partially, by generating a sense of possibilities and expectation in the future.
I don't propose to have the silver bullet answer to just how that is done, and the approach may vary wildly based on circumstances. The ILP approach (replacing the IEP approach) mentioned earlier by Bob Gorman may be one such way of generating possibility and expectation.