A menu that is supposed to be inserted in multiple documents, should be stored to a file.
When you want to re-use the stored menu file in another document, simply insert a Menu object and choose the Insert menu from file option:
When working with stored menus you will gain a huge advantage when it comes to modifications to the menus across you documents. Now you only need to do the modification in one place: The stored menu. The changes you add to the stored menu will automatically take effect in all documents where the stored menu has been inserted.