Change of method of election in any community college district may be made in the manner provided in this act at any time during the period beginning on the first Wednesday in November of each odd-numbered year and ending on the first Tuesday in June of each even-numbered year, if such change is also approved in a manner authorized in this act before the end of such period. The new method of election in such district shall be followed in the election of trustees next following such change and shall continue in force until again changed in the manner provided in this act. Change of method of election shall not shorten the term of any trustee serving on the board at the time the change is made.