Countdownclock time getting restarted when refreshing the page


I am developing an Exam application in Vaadin7. For that, i am using Countdownclock addon to enable timer.

But when i refresh the page, the countdownclock is restarting again.

I need to continue the time from where it left. I mean, it should preserve the time while refreshing.

How can i do that ? Kindly help me to come out of this issue.

Thanks in advance,