@dipesh1010 Changing your domain in itself can have an adverse effect on SEO if the previous TLD’s pages were not redirected to the new one. We have more information on this here: https://yoast.com/video/ask-yoast-switching-tld/
As for the sitemap not updating, whereas the XML Sitemap should dynamically update after any modification to it, if the site or server is caching the sitemap this can cause it to not update right away. We also have additional information on this at the following link: https://yoast.com/help/sitemap-does-not-update/.
If you are not seeing the sitemap as updated, we would recommend checking your caching settings and to ensure that the sitemap is being excluded from the cache.
If the sitemap is being cached by a plugin we have directions on how to add an exclusion for the sitemap files to your cache plugin at the following link: https://yoast.com/help/exclude-sitemaps-from-cache/
If you are still experiencing an issue with the sitemap not updating after checking your site’s caching settings, you can also force a cache reset by temporarily disabling the sitemap feature, and then re-enabling it. To do so please perform the following steps:
In order to disable and then re-enable sitemaps in the Yoast SEO plugin, you would need to perform the following actions:
? In WordPress go to SEO>General>Features
? Toggle the ‘XML Sitemaps’ option to ‘Off’
? Click ‘Save Changes’
? Toggle the ‘XML Sitemaps’ option to ‘On’
? Click ‘Save Changes’
We also have a guide on how to enable and disable XML Sitemaps here: https://yoast.com/help/xml-sitemaps-in-the-wordpress-seo-plugin/
As for purchasing Yoast SEO Premium, it does include premium support where we can investigate this in more detail. Although, until we can ascertain what might be causing it we can’t say for certain what exactly is required in order to correct it, such as in the case of a conflicting plugin for example.