That scene was about Ranru finding a way to remove the Revived Succubus's slime off of their changers. In which, she used one of her devices to do an analyze the goop, which she needed time to do.
Umeko: "What are we supposed to do about this sticky stuff?"
Ranru: It's all right. *Uses device to analyze goop* I just need you to... *Tugs at Jasmine's collar* change your clothes.