§12A-2-209.

§12A-2-209.
   
   (1) An agreement modifying a contract within this article needs no
   consideration to be binding.
   
   (2) A signed agreement which excludes modification or rescission
   except by a signed writing cannot be otherwise modified or rescinded,
   but except as between merchants such a requirement on a form supplied
   by the merchant must be separately signed by the other party.
   
   (3) The requirements of the statute of frauds section of this article
   (Section 2-201) must be satisfied if the contract as modified is
   within its provisions.
   
   (4) Although an attempt at modification or rescission does not satisfy
   the requirements of subsection (2) or (3) it can operate as a waiver.
   
   (5) A party who has made a waiver affecting an executory portion of
   the contract may retract the waiver by reasonable notification
   received by the other party that strict performance will be required
   of any term waived, unless the retraction would be unjust in view of a
   material change of position in reliance on the waiver.