Realized this never got closure.

Since we leveled up mid-battle, I choose another level in sorcerer instead of another level in warlock. That gave me another 1st level slot and sorcery points to recover another 1st level slot. I decided to ignore the yuan-ti with the bow and concentrate of dropping their cleric. It got dicey for awhile, but the crits turned our way for once, and we got away with it.