Reapplying a template to a Sharepoint Site
I needed to reapply a template to a site previously created, but is seems that it is not possible.
At Sharepoint , i created a site applying a template, but then the template changed, and i needed to apply it to the site.
Unfortunately you cannot apply a template to a site once it is created, as far as I know. However what you can do is apply a theme to a site once it has been created. I would suggest using that route or dropping and recreating all of the sites with the new template. Sorry the answer isn't a nice friendly one.
You can find this info at
Reapplying a template