You can retake the CompTIA A+ certification exam if you like to because there is no restriction on the number of limits on the exam or the waiting period between exams. So, if you are not sure that you will pass the exam on 1st attempt, it's better to take the 2nd plan. It consists of Exam Voucher + Exam Retake facility for USD 349, instead of paying another USD 232 (amount for an exam voucher) again for retaking the exam.
If you do not have prior experience, then take up the CompTIA A+ Certification course to ace the exam in one go. Also, check out the following video on the Cyber Security tutorial for Beginners video to help you get a better understanding.