SmartScreen filter is implemented as a webservice by Microsoft. You do not need to manually update the filter.
To confirm this, you can run a network monitoring tool such as Wireshark. You will see requests to Microsoft's SmartScreen filter being sent via a URL.
To request that Microsoft updates their SmartScreen filter, either
a) If you own the site, send an email to secure[A.T]microsoftDOTcom querying the reason for the issue.
b) If you do not own the site, click "Continue Anyway" on the site. This action will be logged by Microsoft and they use this statistical data to update their tools automatically.