PDF Image Previews

I use this plugin frequently to replace pdf files on our website. This part of the plugin works perfectly. However I did notice that with each new pdf that is uploaded to replace an existing one, an entirely new set of jpg image files are created (full size, thumbnail, medium, large). The image files from the replaced pdf file remains on the server and the new ones are created with a -# appended to the filenames. Is there a way for this plugin to replace the associated image files as well as the pdf file? Otherwise my web server is going to get cluttered with lots of unused image files. Thanks!