A plugin taht lets you export only your WordPress menus via the WordPress Export page.
WordPress Menu Exporter lets you only export your WordPress Menus (like you can with Posts, Pages etc). The WordPress Menu Exporter plugin will also export and pages / terms that are referenced in yoru WordPress Menu.
menu-exporter
folder to the /wp-content/plugins/
directorymenu-exporter
folder to the /wp-content/plugins/
directory