I feel your pain, and everybody else's. I had the same issue. Nothing that was posted here worked and for quite some time. A sequence of improvised actions some how did it, and I posted them a while ago. Sorry I do not recall them anymore.
One suggestion I have is this: I have an Apple Airport Extreme router. I recall having to reset it in order to add a new wireless printer. I mean use the reset button in the back of it, not just turn the power off. Once back up and working, I noticed that all kind of related application and peripherals started to work better. For example my iPhone was now connecting much faster to it, my computer WiFi connection was better and faster, and I haven't had any issues with my iPad anymore.
Also, make sure you check your internet provider website. They should have a guide as to how to properly set up your router (brand, model etc). I learned that some settings that perhaps are not properly set could disrupt the iPad connection just as they can some applications using some specific ports or requiring some specific setting either enables or disabled.
Obviously another shot in the dark, but perhaps for somebody it may work.
Good luck.