Hungaroring once again exposed the weakness in W08. So, it doesn't make any sense to add new parts, until they clearly understand the challenges they are facing with the setup for slow turn circuits. They have got a perfect opportunity to slug it off on a circuit that made them vulnerable and come out of it rich in knowledge.
If I understand correctly, they most likely have various internal elements that they might be testing to overcome their challenges to be better prepared for Singapore GP. And most likely be enhancing their understanding of the tyres in relation to their challenges.
They don't have to worry about the other upcoming fast circuits on the calendar.
Besides, it would be time to move resources to W09 and they need to understand if they have any fundamental flaws that they need to sort for W09.