Hi Colonel_Klink,
To do this You should :
1. Go to your "Edit Content Detail" page and press "edit" button neat item You'd like to re-upload.
2. On the opened page You will see "Content ID: ....". Copy it.
3. Start Content Uploader and add new version of content.
4. Press "Replace" button in the upper right corner.
5. In the requester enter "Content ID" You just got.
Hope this instruction will help.
Vit