How to programmatically change PRO SITES blog levels

I am trying to programmatically change pro sites blog level based on blog id. Didn't find the correct solution yet.

I think there it could be done with:

update_blog_option( $blog_id, ...);

is there any hook I can refer to?

I tried:

update_blog_option( $blog_id, '2');
(by default it will be set to 1) but it didn't work.

At this point anything would be consider good to get me closer to this solution.