How to repack an existing sprite sheet?

To repack a sprite sheet, you must first extract the sprites from the existing sheet.

Use TexturePacker's Split Sheet tool to extract the sprites from your existing sheet. Save the individual sprite images in a folder.

Create a new TexturePacker project and drag+drop the folder with the extracted images as a Smart Folder on TexturePacker's left sidebar. TexturePacker will automatically load all images and repack them.