Thanks for your reply Arijit.
I have set the recurring instance for the report while scheduling. The report is set to wait for the specified time period to kick it off for the next time. The report is not getting kicked off if I replace the existing trigger file. If I delete the file and place the new file once again then only the report is getting kicked off. Why it is not getting kicked off if i replace the existing file with the same name and in the same location.(I am thinking it should run even if i replace the trigger file as there is a difference in the time stamp of the file creation).
Also, I have written a VB script for deleting these file. I want to know how to set the dependency between the reports and the script. (Eg: As soon as the report is ran, the trigger file should get deleted).