Melisandre told Arya in Season 3 “We will meet again”
Arya is now back in Westeros, and Melisandre is riding South because she’s been banished from the North. Ergo, Arya will NOT meet Melisandre again at Winterfell. She’ll meet her probably in the Riverlands.
Melisandre is someone who Arya absolutely despises, because Melisandre hurt and took away Gendry from her
So can the showrunners please stop trying to pretend that Gendry doesn’t exist anymore because that reunion WILL HOLD NO WEIGHT AND MAKE NO SENSE OTHERWISE