As per the Birthright contract, if you cancel your trip  65+ days before departure you will receive your deposit back.

Once a trip offer has been officially accepted, then cancelling within 65 days of the trip departure date will result in forfeiture of your deposit. This deadline is imposed by the airlines, and the deposit is used to cover the fees for cancellation no matter the reason. All Cancellations must be formally submitted, in writing, to info@mayanotisrael.com and those made before 65 days will avoid forfeiting of deposit.