The single most important element of a good debrief process is speed. The key is to get these issues/ideas collected and cataloged before anyone forgets them. For me, once the initial input is received, I would send out to all Divisions in the company a list of issues brought up and would then begin seeking volunteers of forming teams to address each issue. Under ICS Team Leaders, Directors and Section Chiefs would be responsible for ensuring the issues are addressed and plans are updated.
The overall goal is to ensure that issues are addressed ASAP and the Plan is updated. The end result should be a living document that is always up-to-date the next time an event takes place. This hopefully highlights the importance of scheduling debriefs immediately after the restoration is complete.