Section 3-4.6. Revocation or alteration of later will not to revive prior will

or any provisions thereof
    (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.