Cite While You Write always creates the initial bibliography at the end of the Pages document that it has formatted. We recommend that you leave the bibliography at the end of the document, but realize that is not always possible.
You may want to add text after the bibliography. You can do this, but make sure you are beyond the end of the bibliography. If you add within the bibliography, it will disappear the next time the bibliography is updated.
You can copy and paste the bibliography. First, highlight the entire bibliography field—but make sure you include the two paragraph markers before the start of the bibliography, plus the complete bibliography, plus the paragraph marker after the bibliography. Then, Cut the bibliography and Paste it in the new location.
Once you have moved the complete bibliography field to a different location in the document, it will stay there even when you reformat the paper.
Another option is to completely delete the existing bibliography and then insert a new one in a different location. See Deleting a Bibliography and then Inserting One in a New Location.