DLC is account bound on PSN so you must re-activate your account in order to access it. There is nothing that we here on the AHQ or even at EA can do to help you with this issue since it's a Playstation Network entitlement issue. I recommend speaking with Playstation customer service to see if they can reactivate your PSN account that has your DLC on it or if they can merge your old and new PSN accounts (Don't know if that is possible but it might be worth asking). You can contact Playstation customer support here:
Sony Computer Entertainment America LLC
Support Site:
www.us.playstation.com/Supporthttp://us.playstation.com/corporate/Contactus Consumer Services Technical Support: 1-800-345-7669
PlayStation®Network Accounts and Billing Support: 1-877-971-7669