While it does not exactly say that the fruits "grow up again", the SBS for vol. 48 contains a question regarding the subject:

With that said, I don't think it's ever been said (except, as deffkryz said above, in Romance Dawn but that's not canon) that they grow back. It would be the logical thing to assume that they do, but it's not confirmed. As Oda-sensei said, we should wait patiently for Dr. Vegapunk to explain it to us.SBS said:D: Excuse me!! May I pose a serious question to the typically-vulgar SBS?? In Volume 46, Usopp said that the same power doesn't exist twice. But this doesn't make sense with what you said in the Volume 45 SBS... If the Gomu Gomu Fruit was in a book of fruits, then Luffy HAD to have eaten at least the SECOND known example of the fruit! Now, most beautiful and intelligent Ei-chan, explain it all! ✩ P.N. Takafi
O: Very sharp of you. But I'm cool. I haven't made any mistakes. As a hint, let me rephrase what Usopp is saying. "The same powers don't exist twice AT THE SAME TIME." How's that? For more detail, you'll just have to wait for a certain professor to make his appearance in the story, and explain exactly what the Devil Fruits REALLY are... Eventually.



Damn it Oda! Tell us right now! 
) with what he felt back then.
