I do not believe there is a fix for fogged windows,other than replacement.

An former associate of mine bought a franchise some time ago, haven't followed up to see how well this worked out for him, but the company offers some interesting options.

Look up "Crystal Clear Window Works" or getthefogout.com

I remember reading a lot about this company in glass industry publications when they began going nationwide, it might be expensive compared to replacing glass but it does give you an option that is not commonly known to exist.

The problem with companies that offer to "vacuum" the fog out of you windows is their methods do not address the reason for the fogging which is a seal failure. They may be able to remove the fogging between the panes but, unless the window is resealed, the fogging will return over time.

I can't say I believe the idea to clean the IG and re-seal it is how I would correct a bad IG. The company that claims they have this figured out also offers a strong guarantee for IG units they have fixed making it their problem if they aren't really fixed.

I recall learning about the group that moved this company to the U.S. (it startd elsewhere). Not a bunch of scam artists but some genuine window experts that decided they had found something that there was a demand for.

I would change the glass if it were for me or one of my clients, but apparently these guys have convinced some otherwise.

Another issue with vacuuming is it doesn't replace the argon/krypton gas. I would also be interested in knowing how they address water stains from condensation on the interior surfaces of the glass.

There is a company at windowmedics.com who claim they can fix the problem without replacing the window(s) for about 1/3 to 1/2 the cost of replacing the window.
Apparently they have developed a one-way valve that allows the moisture to exit but not return. They apparently drill a very small hole in the exterior pane in an upper or lower corner of the glass and after vacuuming the moisture out they install this valve that keeps the dry air in and the moisture out.
They claim that MOST fogging is not due to seal failure. They say that if double paned glass had an impermeable seal that the window would explode when heated by sunlight, expanding the material inside. They say that moisture is actually absorbed by a moisture absorbent material hidden in the frame of the window and when this material becomes saturated after 10-20 years that this is when the fogging occurs.

They also mention that they don't replace lost Argon/Krypton gas but that this doesn't lose that much of the insulating factor. They say the majority of the insulating qualities are due to the air/Argon/Krypton being moisture free and moisture is an excellent conductor of heat/cold. That by removing the moisture they restore most of the insulating factor of the windows.

I can't vouch for them one way or the other, only mention their existence and what they claim about fogging removal because I face having to do something about to large picture windows myself right now. The one began showing a small amount of fog a couple of years ago but this spring all of a sudden both are virtually completely fogged and have water running down the inside of the panes.

So I am looking very skeptically at their ability to fix such massive leakage of moisture into the windows.

While they may be 100% correct for minor moisture buildup I have to believe my windows have massive sealant failure.

When I faced the same problem I had taken the help of WINDOWMEDICS INC. Their expert repair my double pane fogged window.

Here is a link that might be useful: WINDOWMEDICS INC.

There are some negative comments online about Windowmedics and "Crystal Clear," both started by the same person, who has since co-founded PureRay. (Ownership information is from Bloomburg.com.)