At the end of the exam, you would be receiving the following messages regarding the reattempt:
"We're sorry, but you did not achieve a passing score on the exam. If this is your first attempt, you must wait for 3 days to re-take the exam. If this is a subsequent attempt, you must wait for 14 days to re-attempt the exam."
Documented on the Professional Certification overview page is that you do have to take the practical exam within 3 months of passing the written exam.
1.9 - Retake Policy If you fail the requirements of the applicable Certification Exam, you may retake the exam for a second time, after three (3) business days of the original Certification Exam. If you fail the Certification Exam on the second attempt, you may not retry again for fourteen (14) days. You must pay the exam fee for each attempt.
Hope this helps.