There are more settings to be played with in 1and1 control panel they just aren't easily found.
- Log in to your control panel.
- From the home screen, scroll down to the "MANAGE WEBSPACE" section.
- Click the "More >>" link.
- Find the "Content Delivery Network" section.
- Click "Open".
- Select the domain using the CDN.
- From the "Edit" dropdown, select "All Settings".
- I am not sure if this is required, but it won't hurt anything.
- under the general settings...
- Click "Edit".
- Turn on Development Mode.
- Click "Save".
- Rollout the "Performance" section.
- Click "Edit".
- Here you will find an option to "Purge Cache".
- Your images should be updated.
- Make sure to turn Development Mode back off.
There are a bunch of other options available here. Make sure you read up on them before pushing buttons. :D