Hi! Students can return back to Doha if they are under father's sponsorship even after one year. But you have to pay QR 500/- at the Immigration dept. before their arrival. They have to carry a scanned copy of this when they travel for safety reasons. This will not affect their visa status.
Boys need the exit permit from father when they are exiting Doha whereas girls don't need this.
I know this as both my son and my daughter have to go through this process every year as they are studying in India. Hope this helps.