Skwire, I follow you. What about adding a note at the top of the newest, clean clip.txt file that says, "...continued from clip1.txt..." ?
Also, what about, instead of renaming the clip.txt files to clip1.txt, clip2.txt, etc.,
instead, just use an incrementing appendage.
So, a user might have clip.txt (active), clip35.txt, clip36.txt, etc. - but only 5 (or x amount they chose to keep).
Then, when clip.txt is full, instead of renaming any files, you just copy clip.txt to clip37.txt and then clear clip.txt, and adding the note at the top.
This may be less confusing for the user, because the file sequence is obvious. They will always look to the highest number for the last clip file's contents.
Or, and I don't know if you can do this easily,
You could add the note about the last clip file, and have ClipText's viewer make it into an internal hyperlink. Then the user sees the file is new, but can quickly access the last file, whatever it's name is.