How to refresh hosts file without rebooting
You don't need to reboot. Any changes you make to the hosts file are immediate. You used to need to reboot for changes to take effect in Windows 9x. That is no longer the case.
However, you may need to restart any applications that do internal hostname or DNS caching, such as web browsers.
Have you tried ipconfig /flushdns ? I haven't found the need to reboot, though.