Limit Excerpt Length to Paragraph

Hello!

I’m trying to limit (or rather extend) the length of the excerpt in the post slider to the full first paragraph.
Is that possible?

I can alter the length by character using this code:

add_filter('avf_postgrid_excerpt_length','avia_change_postgrid_excerpt_length', 10, 1);
function avia_change_postgrid_excerpt_length($length)
{
   $length = 100;
   return $length;
}

But can’t figure out if its possible to just limit it to a full paragraph.

Thanks!