Mo. Rev. Stat. § 49.570
If the governing body of the county should find that the bonds authorized will be insufficient to supply the funds necessary to complete the project authorized, additional bonds may be authorized and issued subject to the procedure as described and required in sections 49.520 to 49.580. After the issuance and sale of the bonds, if the governing body of the county deems it to be to the best interest of the county, refunding bonds may be issued for the purpose of providing funds for the payment of any outstanding bonds, in accordance with the procedure in sections 49.520 to 49.580. The new bonds shall be secured to the same extent, in the same manner and shall have the same source of payment as the bonds which have been refunded thereby.
§ 49.570, RSMo