If there's not enough probe heat at limit, redesign with more effective heating, perhaps with better insulation on the outer surfaces to prevent heat loss.
So, I take it you know exactly where the ice is forming on or in the probe, and can tell Thales and Goodyear exactly what is wrong with their designs so they can fix them post haste? Or does "only needs the application of some engineering" mean that engineers can instantly design a fix for a problem that they don't understand? (Certainly tens of thousands of engineering managers have demanded this over the years, so clearly it must be a functional engineering approach?)
Or perhaps it is that people THOUGHT they knew how pitot probes worked, and THOUGHT they understood icing conditions at high altitudes, and did the best they could to design to those specs. And with some 70 years of positive experience without failures, it appears that they did a pretty good job. But now suddenly what has worked reliably for 70 years no longer works. Clearly this means it is a trivial engineering job to simply redesign for this never-before encountered (and thus unknown and not understood) change.
Maybe (if you aren't a member of the government, where everything can be accomplished by fiat) it means you first have to start by understanding the problem. And despire the engineers and scientists being ordered by management to provide an instant fix, maybe it does take some time to figure out what is different...