If a change order for any public works contract (i) is entered into by a unit of local government or school district, (ii) is not procured in accordance with the Illinois Procurement Code and the State Finance Act, and (iii) authorizes or necessitates any increase in the contract price that is 50% or more of the original contract price or that authorizes or necessitates any increase in the price of a subcontract under the contract that is 50% or more of the original subcontract price, then the portion of the contract that is covered by the change order must be resubmitted for bidding in the same manner for which the original contract was bid. Bidding for the portion of the contract covered by the change order is subject to any requirements to employ females and minorities on the public works project that existed at the bidding for the original contract, together with any later requirements imposed by law.