how can I link to a PlugIn admin-sub-menu page after processing a formular

how can I link to a PlugIn admin-sub-menu page after processing a formular

I have a Plugin with 3 submenu_pages. In one page is a formular (in one
some text and in one a list of items). when I submit the form, there will
be done some processing. after that I don't want to get back to the
form-page, but WP shell redirect me to one of the other submenu_pages (in
this case a list).
how can I achive this?
add_menu_page( 'page1 main page', '0', 'manage_options', 'mg-pi',
'mg_backend');
add_submenu_page( 'mg-pi', 'list smthing', '0', 'manage_options',
'mg-pi-sub-list', 'mg_list');
add_submenu_page( 'mg-pi', 'create', '0', 'manage_options',
'mg-pi-sub-create', 'mg_new_item');
so in mg_new_item() is the processing and then it shell redirect to
mg_list(). but if I do the php call to mg_list() the url is still the one
of mg_new_item().
I know I could do some header("Location: the-hardcoded-list-url"); but I
am looking for the WordPress common way of doing it, with generic Url
generation.