Probably you have to send the whole set back to re-program them. I don't think HP provides this service that means you have to find elsewhere (if available). Because new dongle NEEDs to talk with your keyboard using SAME code.
I would do this for you and I would charger $200 for this service by simply buy a new set for you and keep the change.
The bottom line is please go out and buy new set. Sorry for a long explanation,
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