Hi Sourabh,
Manually released document will be excluded from all future screening unless a significant change is done in the document like changing business partner and/or its address.
Due to intelligent SPL screening logic, system applies your last decision if the data has not changed since last manual release. so system will only re-screen if any significant changes are done since last release like changes in SPL master data or Business Partner address etc.
If you change Business Partner in your Sales Order or address manually, then it will be re-screened.
Also, check the control settings of SPL screening configured in your system. "Check logic for docs" - this controls whether a re-screening or status check is done for Periodic screenings of document.
regards,
Kul Vaibhav