Urgent Migration of Live Web App

We need to migrate an active web app from an expired domain to a new one. The original domain owner sadly passed away, and we recently discovered the need to transition the site to its new address. The site is hosted on our reseller account with Krystal Hosting, and we require a full migration to a new cPanel, including files, emails, and all associated data. Given that this is a live web app, we also need to expedite domain propagation to minimize downtime.