Try this
Force quit safari. Double tap the home button. Flick the preview for safari off the screen to close it Then single tap the home button to exit the mode.
Then go into the settings, safari and discard your history.
For good measure you can force your iPad to reboot, just to clear out the cobwebs. Hold down the sleep and home keys for about 20 - 30 seconds. When you see the silver apple, let go and let it reboot.
Try your site again. However, even if that fixes the issue, if the site has a browser hijack ad on it you will keep experiencing the redirect whenever that ad comes up. You can try an adblocking app (I use weblock). If the issue persists after you clear the browser cache then you may need to research your router being infected.