We allow the wealthy to displace the homeless from unoccupied buildings whether or not they have a better use for them and whether or not the displaced people might be expected to die as a result.
Presumably that means that most of us hold moralities that allow this to happen.
If nothing else, our organs are our most closely held piece of personal property, and it is never inappropriately earned. They are naturally given in utero, and all maintenance and growth are the work of one's own body. So in any morality that allows for properly acquired wealth to be unequal enough to cause starvation, and for stolen wealth to be reacquired by the holder, it would be within your right to reacquire the organ.
Such moral systems tend to be hard to ground theoretically or to state clearly.
I do think Kant, or some more naturalistic version of "limited interchangeability" imposes a more limited right to private property, and an obligation to make some attempt to support those in desperate circumstances. And that you can derive advice here directly from Kant.
We can consider that the person taking another's property is always addressing them as a means, and not an end-in-themselves.
You can rule out the notion that one may steal to stay alive, because one can never really know the consequences of one's theft, and it might simply cause another's death to take place in your stead. It is better if the reallocation of goods takes place in a way that is effected more indirectly, so that it cannot be used too easily as a weapon.
But it is difficult to uphold revenge or recovery in Kant, because we see how it leads directly to endless revenge when two sides disagree on the value of the things taken or retaken. In this case, the value of the organ is seriously different for both sides, but still quite high -- we all have two because they tend to wear out, so if I let mine be taken, I might die younger.
At the same time, a complete right to retain property, that regularly results in death, is itself a weapon, aimed at the destruction of the 'surplus population', and treating those who do not fit well into society as means and not ends. Witnessing suffering degrades future moral capacity unless one responds to the empathic pull that is the sentimental reflection of duty. (This is harder to base directly on theory, but it just seems obvious. And it is a lemma Kant derives in making his argument for limiting one's consumption of animal products to what can be produced without cruelty.)
When communities have themselves set up mechanisms that attempt to prevent the poor allocation of goods from resulting in death, it is best that everyone be equally subject to them. So, since in this case there is a vast system for voluntarily donating and recovering organs, theft of them should be discouraged, as it will degrade that system.
From that I would propose that I should be prevented from taking back the organ, but that I should be placed on whatever recipient list the individual stealing it would have occupied. I do have some right to recover the stolen goods, but not to kill in the process, and there is a way for this to happen.
Since I think you should be prevented from threatening the holder's life, whatever his relationship to the threat, your follow-up question doesn't come into play.
How recompensation for the organ itself should be managed is a really difficult call. If the person who needs the kidney bought it on the black market, for instance he has substantial money, and that could be used. But if the sufferer is really basically impoverished by his illness, he has a debt that he will not be able to pay.