I would call the sheriff's office and clarify that point. I just received my CCW permit renewal from the D.C. sheriff. It's the same form as for a new permit, but doesn't require the proof of firearm training. On the instruction sheet, the sheriff's office crossed out the part about needing to have the form notarized. I believe the sheriff's deputy who takes your fingerprints and photo will have you swear to the truthfulness of your application.
In the case of a renewal, the sheriff's office sent me another form which isn't on the website which is an affidavit of continued firearms qualification. That form has to be notarized.