How to upload new versions of an image with the same access path?
You can try the Upload File Replace module, This module solves that problem by swapping the names of the older and newer file so that the newly uploaded file will retain its original name.


  This is a small utility module that automatically stops Drupal from
  renaming new files upload via filefield CCK. When 2 files with the
  same name exist, the older files will be renamed.