Table event 'After saving' for date delimition

I have created a custom table which has stat date and end date. Whenever a new record is created and saved,

The default value for new records must be 12/31/9999. When user creates a next record, the existing record must be automatically. delimited to BEGDA minus one.

I have implemented the code in 'After Saving' event where the delimition happens correctly. But once i save and click on exit button, again it's asking to save the record. if i save the delimited records are not updated.

Please provide some solution on this.

Regards,

Stanley