How do you repost pictures from Instagram on an android?

Instagram

You can! - In response to previous answer stating the opposite :)

1. Load up Instagram
2. Go to take a new photo by clicking/pressing on the camera icon
3. Next, click/press on the gallery icon instead
4. Locate the Instagram album from your photo gallery and select it

(Most Android phones will store Instagram photos in their own album)

From here you can crop your image, (DO NOT apply new filters if your image was previously processed with filters) hit accept, post to your favorite social network and DONE!