Stick that filename into some space, and then use that value in the HTML "value=" statement in the input field.
IE, if you used the session array, have your handler script stick that info in a session var, and have the form say
<input type=file name=userfile value="<?php echo $_SESSION['imagefilename']; ?>">
Well, I'm thinking it'd work ...
An alternative might be to check for the existence of the file, and return an error there as well ??
HTH,