There are 3 books in the The Looking Glass Wars series. The newest book is ArchEnemy which came out in 2009.

1
The Looking Glass Wars

Book cover of The Looking Glass Wars
The Myth: Alice was an ordinary girl who stepped through the looking glass and entered a fairy-tale world invented by Lewis Carroll in his famous storybook. The Truth: Wonderland is real. Alyss Heart is the heir to the throne, until her murderous aunt Redd steals the crown and kills Alyss?…
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2
Seeing Redd

Book cover of Seeing Redd: The Looking Glass Wars, Book Two
Wonderland finally seems as if it’s getting back to normal. Queen Alyss is back on the throne, and reunited with her childhood sweetheart, Dodge. But the fight for Wonderland is far from over. King Arch, in nearby Boarderland, is conniving to overthrow everything for which Alyss and her friends have…

3
ArchEnemy

Book cover of ArchEnemy: The Looking Glass Wars, Book Three
The Heart Crystal's power has been depleted, and Imagination along with it. The people of Wonderland have all lost their creative drive, and most alarmingly, even Queen Alyss is without her powers. But at least the vicious Redd Heart seems to be similarly disabled. Amazingly, she is attempting to team…