No need to amended the Constitution, you need congress to pass a bill correcting the misinterpretation of the citizenship clause in the 14th amendment. It will of course be challenged in the Supreme court, however if the legal argument is based on the intent of the author (Sen.Jacob Howard) of the 14th amendment, the new interpretation would stand. Jacob Howard wrote the citizenship clause in the 14th amendment based on natural law and not common law. Natural law is basically saying one can not pass on to others that which they don't themselves posses if neither parents are American citizens than neither will the children be.