In One Piece, does a Devil Fruit reappear after the user dies?
Taken from the One Piece Wiki on Devil Fruits:


  When a Devil Fruit user dies, their ability is reborn into another fruit of the same kind. Instead of growing from a plant, the ability simply regenerates inside the closest appropriate fruit, as seen when Smiley "died" and the Sara Sara no Mi, Model: Axolotl transplanted itself into a nearby apple. Another characteristic of a Devil Fruit's growth is that the stem becomes noticably curlier than it was when the fruit was not endowed with the ability.


So, in other words, the Devil Fruit "respawns" when the user that had it dies.