You can have updated report results delivered to you on a schedule by using recurring reports.
After you've saved your report and gotten results, you can set up recurring reports in the "Recurring Reports" tab on the report's manage page.
To set up a recurring report, set the interval you'd like the report to recur (daily, weekly, or monthly), an optional start date for the recurring reports (ex: set the first of the month if you want monthly reports to start on the 1st), and the email addresses you'd like to receive a notification when the report runs. Click "Save" to save your options.
When the report is set to recur, the targeting will re-calculate and an email will be sent to people set up to receive the notification, telling them of the new count and giving them a link to download report results.
To stop the report from recurring, remove the email addresses or the interval from the "Recurring Reports" tab and save.