Sarah
The way that cross-references work is that Word puts in a hidden bookmark around the source text. Then the cross-reference includes the name of that bookmark in the field code. What this means is you can redefine the bookmark to enclose the 19 instead of the 18. Then all the xrefs to the same bookmark will automatically update to point at the new location.

To fix the problem, reveal the field code on one of the xrefs and copy the bookmark name. The field code will look something like this {Ref _Ref12345678 \h}. Copy the _Ref12345678 text and then navigate to the location of the endnote which is now #19. Select that text and add a bookmark with the name you copied in the earlier step. Then just update the fields.

In some versions of Word you can't add a bookmark via the GUI if it starts with an underscore (ie it is a hidden bookmark). If this is the case with your version of Word you can add the bookmark via a line of VBA code or you can toggle all field codes and do a search/replace to change the bookmark name (in all the Ref fields) to something you can add via the GUI - and then set the bookmarked area with that name.

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Andrew Lockton
Chrysalis Design, Melbourne Australia