At this point, I would suggest logging in to your shop.weavertheme.com account. Then open Your Account -> Your Licenses -> View Details and Downloads. If your license is still active (which it should be since you are getting notices to update), there will be a link do download the plugin file under the Products section.
Download that, and then open the dashboard plugins page, click add new plugin, then upload plugin, and upload the file from the first step. WP will then allow you to used the new file to replace the old version.
See: https://guide.weavertheme.com/weaver-xtreme-plus-installation/