After that loss, things had kind of...stagnated. There was no way of getting successfully in and out of Gringotts without Griphook’s help, and without the sword they couldn’t destroy the cup anyway. All stealing the cup would do was alert you-know-who to the fact that they were actively seeking out his horcruxes. So they had done what they had called "regrouping’, but what was really just giving up, in Hermione’s opinion.