The Grand Rewind is a much more powerful version of the Prince's standard rewind powers. The Grand Rewind is only seen once in The Sands of Time, but the ability is used many times in Warrior Within as he uses the various Time Portals scattered along the Island of Time.
Unlike a rewind, a Grand Rewind can be set to go before any event in the timeline. In The Sands of Time, the Prince uses it to go before the Persia's final attack on India. In Warrior Within, he uses it to go before the creation of the Sands.
The Grand Rewind is not used at all in The Two Thrones. However, the Prince is teased by his Darker form after he finds his father's dead body that he should do a Grand Rewind and make sure that his father wouldn't die.