Change Custom POst Type slug

Hello.
I have a custom theme with custom post types, can be edited from my admin panel. I don’t understand how is this theme register custom post types (i didnt find any calls to register_post_type()).
And i need to change custom type slug. For example i have ‘services’ post type and all posts can be accessed from domain.com/services/some-post-slug. and i want to change this to domain.com/some-name/some-post-slug.
(i odnt think that simple rewrite will help me – i need to change all internal links too). I can get_post_type_object() and there is slug, but i cant change it. and i didnt find this in db.
thanks