37 C.F.R. § 1.958
Petition to revive inter partes reexamination prosecution terminated for lack of patent owner response
If a response by the patent owner is not timely filed in the Office, a petition may be filed pursuant to § 1.137 to revive a reexamination prosecution terminated under § 1.957(b) or limited under § 1.957(c) if the delay in response was unintentional.