I might have spoken too soon. Having the plugin set to opt out messes with other functions I'm using (I have a canvas object being added over and over now). Is there anyway to add an attribute, 'data-swup-reload-script' to the showsrtemplate.js file added to the head?

Thanks for your reply. I'm using the technique you linked to already. The solution was one I'd already tried, a Swup plugin which forces js in the head to reload. https://swup.js.org/plugins/scripts-plugin

I just had it set to optin which means I would have had to add a data attribute to the showsrtemplate.js. I doubt there's a way in Shopify to add attributes to scripts added to plugins so the plugin is now set to optout and the reviews load correctly.

Thanks for your help.