Reminder notification for task

I have designed a workflow where an email is sent to user when task is assigned to him. If task is not completed within 2 hours then an escalation email is sent to user by keeping his manager in CC. I want to send a reminder mail to user for every 10 minutes. I have tried Non-Interrupting timer but it is triggered only once. I want it to be invoked in cycle. How it should be designed?