Jakobsen, you can export defects, stories, tasks, etc., but there is no way to export a custom page. If you're looking to have an emergency copy of shared pages, the Sub Admin can request a Sandbox Refresh. This will copy your Production environment to the Sandbox environment, keeping a safe copy. This would not allow you to import the custom pages back into Prod, but you would be able to login to both environments and recreate the custom page - you would have something to reference while recreating the page.