Switching to live domain name

Hi,
we develop our projects under a temporary development URL (http) before they go online under their final domain name. During the development phase, downloads are created via “Select from media library” and work flawlessly. As soon as the project goes online and the live URL is defined for the WordPress and website address (https), everything works fine… except for all previously defined downloads, whose URL still refers to the previously used development URL. Logically, visitors then receive a security warning. In short: the newly defined URL is not taken into account for the created downloads. Am I missing something? What should I do? In the past, it was sufficient to recreate the downloads manually, but a current website in the development stage already has 450 previously created downloads…
Thank you very much for hints!