If I am getting your question right, this is what you have to do:
Write a program which does following:
1) Gets the list of installed services:
ServiceController[] services = ServiceController.GetServices();
2) Check whether your service is running or not using
service.Status
3) Use a Timer control. Set Timer to 15 minutes.
Write code for step 1 and 2 in the Timer_Elapsed event.
Hope this helps.
Cheers!!!
Ankur