You can also just edit the song and change the page order in the song editor in MobilesheetsPro. I'm not sure why the page order isn't being set to 1-5 though. The logic is supposed to determine if the page order previously used all pages of the file, then the new page order should switch to using all of the pages in the new file. I've tested this many times and it's always worked for me. I'm not sure why it's not working your case. It's possible something is different about the environments/folders/files we are using with MobileSheets. I know for certain that the page order will be updated correctly if you use the swap file feature (Select song, tap overflow menu->Swap File). Are you just replacing the file on the file system? That probably won't update the page order in the same way. I may have to look into that.
Mike
Mike