All metainfo records specified in the MetaInfo Dashboard of JSitemap are associated to unique URLs, so if you change URLs of the website the related metainfo won't apply anymore and will be lost.
If for some reason you need to change the domain of your website, for example to upgrade to the 'https' protocol or switch between www/non-www, the easiest method to reapply existing metainfo to new links is the following one:
- Export in the backend, clicking on the toolbar button 'Export metainfo', all existing metainfo associated to links belonging to the current domain, for example http://www.mysite.com. Notice that to do this you have to access the Joomla! backend using your existing domain http://www.mysite.com/administrator or to have configured JSitemap to use the domain http://www.mysite.com for sitemap links
- Use a text editor of your choice to replace automatically all links domain included in the exported csv file, for example to have all links pointing to the new domain https://www.mysite.com. Take care to use a raw text editor such Notepad to not alter the CSV file format, it must use ; as the separator and " as the text delimiter, in the same format that it has been exported, otherwise nothing will be imported.
- Import in the backend, clicking on the toolbar button 'Import metainfo', the csv file including all new replaced URLs. Notice that to do this you have to access the Joomla! backend using the new domain https://www.mysite.com/administrator or to have configured JSitemap to use the domain https://www.mysite.com for sitemap links
Take care when dealing with the exported file in CSV format. If you open it with a wrong editor or wrong editor settings that could be broken, thus importing it back could not work anymore. It's a CSV file using ';' as the fields separator and " as the text delimiter, after editing it must be imported exactly in the same format.
Notice that starting since version 4.4 a new feature has been added to migrate automatically metainfo data from http to https links. This is particularly useful if you have migrated your website to https. After the migration to https, you can open the Metainfo Dashboard and just click the button below to have all previous metainfo data assigned to old http links applied to new https links.
As an alternative you could even change and update directly all links stored in the database through phpMyAdmin, metainfo records are stored in the database table named #__jmap_metainfo
NOTICE: it's strongly discouraged to have double domains website, so you are not going to have the same website working both with http:// and https://. It's a bad SEO practice, you should rather redirect your domain from http:// to https:// using the htaccess and flag the preferred domain in your Google Webmasters Tools/Search Console account. If you really want to manage 2 different domains for the same website, take care that you will have to manage double entries even for the Metainfo Dashboard