If you wanted to repeal the 17th amendment you would have to propose a new consitutional amendment to do that,
You could model it on the 21st amendment, see http://www.law.cornell.edu/constitution/constitution.amendmentxxi.html
Article V of the constitution prescribes the process of amendingit, see http://www.law.cornell.edu/constitution/constitution.articlev.html
http://www.law.cornell.edu/anncon/html/amdt17_user.html#amdt17_hd1 describes why the 17th amendment was adopted:
The ratification of this Amendment was the outcome of increasing popular dissatisfaction with the operation of the originally established method of electing Senators. As the franchise
became exercisable by greater numbers of people, the belief became widespread that Senators ought to be popularly elected in the same manner as Representatives. Acceptance of this idea was fostered by the mounting accumulation of evidence of the practical disadvantages and malpractices attendant upon legislative selection, such as deadlocks within legislatures resulting in vacancies remaining unfilled for substantial intervals, the influencing of legislative selection by corrupt political organizations and special interest groups through purchase of legislative seats, and the neglect of duties by legislators as a consequence of protracted electoral contests.
I hope this information is helpful.