In VM i have created a scan and the scan is finished .Now i want to run it again but at particular date and time how can i do it.
You need to set up a Scheduled scan from Scans > Schedules > New > Schedule Scan.
Provide your desired date and time and mark it to end after 1 occurrence - so it's a one-off scan at your desired time.
You'll find more here: Schedules - The Basics
This is easily done via the "schedules" tab under "Scans." You may want to take the free Qualys VM training to better familiarize yourself with these and other functions of the portal.
Retrieving data ...