I was intrigued so I played around in B2K and found a method. Select all of the page numbers that need changing by highlighting the complete portion (e.g., print page numbers 7 through 200). Go to Menu, Do, Page Numbering, select the Print Number tab, then click the Group Adjust button. You can enter in the adjustment desired: in your case, down by one or -1 (a message in red appears if page number conflicts will occur). There is a checkbox on whether to ignore conflicts. Finally, click Adjust to execute. Obviously one way to do it, but hope you found an easier method.