The following article has steps you can take to update your published book on the iBookstore:
Thank you for using Apple Support Communities.
Thanks for the link, but I have a question regarding the steps in the article.
It says that most of the required fields will be filled in, but in my case, only the title and length are populated. All the pricing, target audience, ect. is blank. Even the ISBN number is gone.
Is there something I'm missing? I followed all the steps exactly as stated.