Kosher After Theatre?
Ladino Tapas - The food is only OK, but it's a fun place for after theater tapas, drinks
La Marais - more of a dinner place, truly excellent food, check what time they close
Tiberas - I think it stays open all night. I've been only once, last month, I had some sort of panini, and it was wonderful
There's La Marais on West 46th which I believe (may want to call and double check) is open until midnight or later. While it is a steakhouse, you can order appetizers and desserts for your "lighter fare." They have a well diverse drink menu.
Otherwise, Tiberias on East 34th is dairy and open 24/6.