(a) Unless otherwise provided in the bond order, if the proceeds of bonds issued to pay for a project are not sufficient to pay the cost of the project, the county may issue additional bonds under this subchapter not to exceed the amount of the deficit.
(b) If permitted by the order originally authorizing bonds to pay for a project, the county may issue additional bonds for improving, repairing, or extending the project.

(c) Bonds issued under Subsection (b):
(1) may be payable:
(A) solely from a pledge of the net revenue of the project; or
(B) from the net revenue of the project and the imposition of an ad valorem tax; and
(2) must be approved at an election in the same manner as bonds originally issued to pay the costs of the project.