No will or codicil, or any part thereof, which shall be in any manner revoked, shall be revived otherwise than by the re-execution thereof or by a codicil executed in manner herein-before required and showing an intention to revive the same; and when any will or codicil which shall be partly revoked, and afterwards wholly revoked, shall be revived, such revival shall not extend to so much thereof as shall have been revoked before the revocation of the whole thereof, unless an intention to the contrary shall be shown.