Board Thread:Questions and Answers/@comment-11398218-20130629184317/@comment-5398287-20130810064450

Erm, you're thinking of Shikai. That regenerates upon its Shinigami infusing it with Reiryoku. None of the Bankai I mentioned regenerate. If you're referring to Ichigo's shihakusho, it does come back naturally-ish because it reflects Ichigo's Reiryoku, but the one time it was "regenerated", Unohana had restored Ichigo's Reiryoku, so it would normally not happen as fast. But that's the only part that comes back.