Set Up Your Scene: make sure a Grease Pencil object with a Time Offset modifier is present. Use Fixed Frame mode to animate the modifier to specific Grease Pencil frames.
Prepare for a New Frame: Click the duplicator button (Time Modifier icon in the Dopesheet header).
Dopesheet Header
Draw: switch to Draw mode and create your new artwork on the duplicated frame.
Re-enable Time Offset: toggle the modifier back on to resume playback.
