Since the Dubnium release, the SIAM Mapping page now provides an easy way to move mappings across different environments and instances without having to cut and paste each map. This feature allows you to import a mapping from an XML or JSON file, as well as export a mapping as an XML or JSON file. To utilize it, navigate to the SIAM Mapping page and notice the two buttons circled below.
The left one is for importing a mapping, and the right one is for exporting a mapping. For more information on this feature as well as others on the SIAM Mapping page, see the documentation.