The 17th could be repealed, but practically speaking it would have to be done by the states calling for a convention, since I doubt that 2/3s of the Senate would vote for it. Why the states back in 1913 didn’t or couldn’t realize that the 17th amendment was stripping their power in the federal government, I can’t explain.
It's the same reason why the anti-17thers can't explain why all those wonderful state-legislature appointed U.S. Senators enacted the 16th amendment (federal income tax) back in 1913, BEFORE popularly elected Senators, if they were supposedly serving "state interests" back then and wouldn't DREAM of imposing some horrible federal mandate on the states.
The answer, of course, is that these state legislatures just aren't the "vision of the founding fathers" utopia that Mark Levin claims they are. Many are as bad or WORSE than the federal government. Hence, the reason the 17th amendment was created in the first place.