A preservation trust may be established as a revocable and amendable trust or as an irrevocable trust. If the grantor of a preservation trust revokes or partially revokes the preservation trust, the exemption provisions of Section 12 of this title shall not be applicable to any property received by the grantor as a result of such revocation or partial revocation. The fair market value of any property received by the grantor as a result of a partial revocation shall increase the amount of property which the grantor may contribute to the preservation trust pursuant to Section 12 of this title.
Okla. Stat. tit. 31, § 13