The patent owner can request a re-examination any time during the life of the patent to narrow claims and, with the AIA, anyone can request an Inter Partes Review to challenge the validity of a patent. That is a relatively expensive process. These are not specific to the grounds of a claim going beyond the disclosure but can be used to remedy/attack claims for many reasons of defect/validity.
Under re-examination process in the U.S.(initialed by the patent owner) an issued patent can be broadened within two years of the initial grant. Assume the combination a + b + c + d was granted but the patent owner now thinks it should not have been granted due to inadequate support for c being part of the combination. A broadening re-examination could amend it to a + b + d. If there was already a claim to a + b + d the re-examination might not be needed.
In the case of an IPR a patent owner has the right to make amendments to claim the board finds invalid. However, in practice this is a difficult process requiring the patent owner to prove that the amended claim would be valid. There are no actual examiners at the board or involved with the IPR process.