Why do you need to transfer it ? If you bought over the site or something, maybe a simple email to your customers that you bought over the site and that you need them to renew their subscription through your account and tell them that if they do not do that, they be cut within a reasonable timeframe and if they sign up now, they will get some sort of an early bird reward.
Well its best asking Paypal for this then , but i dont think thay will allow it best to just tell people to renew the subscription.
we had a similar problem with a membership site we purchased which had annual recurring subscriptions setup in paypal. unfortunately subscriptions are linked to 'account' not 'email' so even a transfer of email address to one account to another will not transfer subscriptions. our option was to turn it to our advantage and upgrade all members to lifetime memberships - worked great for our reputation and brought in a wave of referrals.