It's great to see Nagatoro trying to help Senpai and boost his self confidence. You can tell that she get's downright mad whenever Senpai downplays himself by saying the only thing he's good at is drawing. Nagatoro wants Senpai to see more of the aspects of himself that made her like him in the first place (even if Nagatoro will not verbally admit that Senpai has said qualities), namely Senpai's passion and dedication to what he sets his mind towards.
I like how Nagatoro's teasing is now more based on trying to motivate Senpai rather than teasing for the sake of teasing. I also like that Senpai is picking up that Nagatoro wasn't just simply making fun of him for kicks, if I'm interpreting him saying "You didn't have to go that far!" correctly.
Also it's funny that Nagatoro calls Senpai a pervert all the time since she always has a perverted grin whenever she sees Senpai checking her out and blushing at the sight of her.