(a) If after executing a will the testator executes a later will which revokes or alters the prior one, a revocation of the later will does not, of itself, revive the prior will or any provision thereof.

(b) A revival of a prior will or of one or more of its provisions may be effected by:

(1) The execution of a codicil which in terms incorporates by reference such prior will or one or more of its provisions.

(2) A writing declaring the revival of such prior will or of one or more of its provisions, which is executed and attested in accordance with the formalities prescribed by this article for the execution and attestation of a will.

(3) A republication of such prior will, whether to the original witnesses or to new witnesses, which shall require a re-execution and re-attestation of the prior will in accordance with the formalities prescribed by 3-2.1.