How to refresh date time when the app is reactivated in WP

Question

i would like to know if it is possible to refresh date time when the app returns from a deactivated state in WP7.5. My app is basically a calendar type and when the app starts the current day is highlighted.

So if i start the app, then press the start button, my app goes to deactivated state, then go to settings and change the time zone, naturally the date and time may change and then come back to my app, it retains the old date.

eg. Suppose current date is 20 and we change the timezone where the date is 19, ideally my app should highlight 19, but it does not. I assume that its becomes before the app goes into deactivated state, it stores all the states and when it returns, it loads the same data. Is there anyway i could refresh the datetime?

Alfah