Plan B or other emergency contraception pills (ECP) are not approved to prevent pregancy for sexual activity that occurs after taking the pills. In your case, you would be advised to take the ECP within 24-72 hours after unprotected sex again.
Another option I advise women who take ECP frequently is the use of a regular form of birth control such as the oral contraceptive pill.
These Q&A’s are for educational purposes and should not be relied upon as a substitute for medical advice you may receive from your physician. If you have a medical emergency, please call 911. These answers do not constitute or initiate a patient/doctor relationship.