If you look further up that page 15 that you reference, it seems pretty clear (my emphasis).
"10.2.1 When is a declaration to be completed?
This declaration may be completed at either the point of sale or the point of claim for policies taken out before the end of April 2006. For policies commenced on or after 1 May 2006 the declaration must be completed at the time of the inception of the policy."
From 1 May 2006, if you are not non-resident at the time of inception, then you can't do the declaration - and there is no scope to do it at any other time.
I found the Irish Life document with a search for 'Ireland life assurance exit tax' - 3rd item after two revenue.ie links.