California Code, Government Code - GOV § 53509

(a) Any bond issued under the authority of this article may be refunded pursuant to this or any other applicable law.  Any bond may be refunded pursuant to this article regardless of whether the bond or the legislation under which its issuance was authorized explicitly provides that the bond may be refunded.

(b) Refunding bonds shall not be issued if the total net interest cost to maturity on the refunding bonds plus the principal amount of the refunding bonds exceeds the total net interest cost to maturity on the bonds to be refunded plus the principal amount of the bonds to be refunded.  Subject to that limitation, the principal amount of the refunding bonds may be more than, less than, or the same as the principal amount of the bonds to be refunded.