Using minuscule amount of it as a reactant to prevent a go to completion so that some of the sodium remains...wouldn’t that work then as it would reheat the remaining sodium oxide.
H2O(l) + Na2O(s) yields(heated) H2O(l) + Na2O(s) through a double displacement reaction right? If I were to use amount of it to superheat the sodium or a surrounding conducting metal, wouldn’t that work? The fact that water evaporate though would pose problems so another compound of 1+ or 1- valence would be used.