(a) Any municipal improvement district of any city of the first or second class or incorporated town of this state shall have the power to fund and refund its outstanding indebtedness, including its bonded indebtedness and accrued matured interest on the indebtedness, and to extend the maturity of the indebtedness on such terms as the commissioners of the district shall deem for the best interest of the district. To that end, the district may issue the negotiable bonds of the district, with interest coupons attached. These refunding bonds shall run for a period not exceeding fifty (50) years from date thereof.
(b) The commissioners of the district may exchange new bonds for outstanding bonds, including accrued matured interest thereon, or may issue and sell new bonds and use the proceeds thereof to take up any of the outstanding bonds or other indebtedness of the district in the refunding thereof.
(c) These refunding bonds shall not be issued in a greater amount than is necessary to pay the outstanding bonds and accrued interest coupons then being refunded, with interest to the date the new bonds are delivered, plus expenses incurred in connection with the issuance of the new bonds. They shall not be delivered except upon the surrender and cancellation of a proportionate part of the indebtedness being refunded.
(d) These refunding bonds shall bear interest at such rate or rates as the commissioners shall provide in the resolution authorizing their issuance.