Any law that is upheld by a referendum called by citizen petition can be changed or repealed only through:

Another direct popular vote

Explanation:

People tend to carry out referendum when they don't like who's in authority or occupying a particular office. When the votes are upheld by referendum, another vote or election or change to that which has been done is by carrying out a fresh vote.

answer; /// the need to make choices because economic wants exceed economic means;

answer; ( correlation );