The question, I suppose, becomes "can you become unfamiliar with someone due to them dying?"*

And the answer will depend a lot on the setting and the individual. You're not Sending to anyone in Eberron who faded away from Dolurrh, nor would you (in my opinion) be able to Send to someone whose soul juice got reformed in Avernus into a devil. They've changed too much, at that point, even if it is the 'same soul'. But other times, sure, potentially.

*also raises the question of if you can become unfamiliar with someone prior to them dying and...it's unlikely to come up in a campaign in my opinion but I would also say yes, you can, in rare exceptions.