I don't think she will come back unfortunatly.
I just take a look at her website today, and saw that she has some health problem which constrain her to stop her career.
"Dear members of LS,
I wanted to say you that the set "Ultimate" of the 05 May 2012 was my last published set, and that Im very sorry to leave you so fast and without warning but my health situation doesnt allow me to wait anymore…
Even if I took really good care to be in the best condition for my work, unfortunately some things cant be changed :(
I tried my best these years when I was shooting and hope you enjoyed it and liked it. I will never forget your sweet comments, and your lovely words! They so often changed my mood from very sad to very happy! It was a beautiful time for me and I will never forget it!
Thank you so much for everything you made possible, and I wish you all the best!
Your Lizzie. Kiss."
I wish her the best, and hope she could come back in few month.
More information here :
http://www.lizzie-secret.com/