@DoOver — I would say for AUD 4 weeks is more than enough time, so don't sweat it. However, you should consider that my advice might be skewed due to the fact that AUD came very natural to me and the questions were extremely intuitive (I'm an auditor). Based on the fact that you knocked out FAR & REG first shot w/ very respectable scores coupled w/ your close score of a 72 I'd bet money that you'll be more than prepared and most likely score 85+ on your second attempt.
To answer your question though, yes the material will absolutely come back to you. The FAR retake was a little more daunting because I had to “relearn” the insane amount of material that is encompassed in FAR. With AUD, you don't have nearly the amount of ground to cover as far as volume.
I see you're taking BEC around the same time as me. How are you doing? I am learning that I hate this material more than any of the other 3 sections by a wide margin. Maybe it's because it's my last section and I'm fed up with this exam altogether, or maybe it's my passion for hating material where I am remembering definitions (IT, COSO, Business Strategy) like my useless marketing and management classes back in college business school. I think it's safe to say that the majority of people will take very little from this BEC section and apply it to their careers.