You must be in shock. Having already submitted, I think you have no choice but to retake in August. But I would consider studying to be your full-time job until the test is taken: no job, no classes, no fun, or you will never pull this disaster out of the basket.
Getting your score back in September makes you a "late" applicant, so you won't have the statistical chance of success you'd have had if the first score was competitive. But it is still possible to get admitted even when applying very late in the cycle (I applied in November and still got in.)
Single-mindedly ride the adrenaline now coursing through your veins and succeed. Be distracted and the second test will also be a waste of money. Can you do it? If not, do not proceed with this cycle. Instead, take a formal prep course, and retake at your leisure, then try again next year.