Hi @infogoldweb-lt
You can take a look how to update a field here: http://www.advancedcustomfields.com/resources/update_field/#usage. I believe it works for a newly generated post too.
You can also check the structure of the repeater by creating a post with the repeater and show it using this code:
echo "<pre>";
print_r(get_field('repeater_field_name'));
echo "</pre>";
I hope this helps.
