OR ... if this is not a networked template,
and you open it normally from the "Files - New" folder,
You could open a copy of the template,
make the revisions,
and "Save As",
Remove the "1" appended to the end of the template name,
therefore using the original template name,
And save as a template again (.xlt).
And answer "Yes" when asked if you wish to overwrite the original file that
already exists.