Did you know that you can change the post type when you Reblog? After clicking the Reblog button, click the gray “as…” button at the top of the screen. There you’ll be able to choose a different post type if you like.
This can be particularly useful when you want to Reblog a lengthy Text post. Tumblr will sometimes convert it to a Link to save space on the Dashboard, but you can always click “as…” and then choose “as Text” again.