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Not really. Around me it's $75 to $150 to restore each sash. You could end up repairing the fogging issue and then find the frames fall apart a few years later. You're dealing with an inferior window already, so it would be wiser to replace them and have a warranty again.
If they're already replacement windows of stock or normal sizes with fillers and you're somewhat handy, you could very easily and cleanly re-replace them entirely for as little as $130 each and still end up with a better window and better efficiency and comfort.