If you want it to run say, every hour you could create a cron tab by doing:
Edit your crontab:
# crontab -e
Type this in the file:
1 * * * * /root/scripts/freshen_dir.sh 2>&1 >> /var/log/freshen_dir.log
You would of course need to name this script "freshen_dir.sh", and mv it to /root/scripts.... change that to whatever you want.
The "2>&1 >> /var/log/freshen_dir.log" will send all output (errors and std_out) to a log file for review.