Make my shell script die when finished.

I have a shell script that FTPs files from HP-UX to a Novell server every 5 minutes as an upload. Sometimes the previous upload script hangs out there so the subsequent uploads won’t run because they grep for the script and see it still out there. How can I make a script die better when it’s finished. Sometimes these hang for 2 hours or until I kill the PID for the script then in 5 minutes the next upload can run.