Go to your B&N Library on the nook and check for new content. Highlight the book and reopen, it should have all the pages. If that doesn't work, open a different book then reopen the new book.
The second option worked under 1.1.1 but under 1.2 the one sample I've purchased updated to the full book without problem.
If you are still running the old version of the software you might have to log into the website, delete the sample from your library, archive the whole book then download again to the nook after checking for new content.
The newer software version 1.2.0 solves this.