60 ILCS 1/115-25

If the board recommends any amendments or additions to a plan that has been adopted by a township, no property that is the subject of the amendment or addition may be acquired until the revised plan is approved by the voters at a referendum under Section 115-20 unless the amendments or additions do not provide for expenditures in excess of those provided in the original plan and do not provide for the acquisition of property other than from persons who are selling their property voluntarily.