Uhh...I really didn't get your question? Do you mean to ask that how can you use WriteAgain! for a Blogspot Blog?? If that's what you want to ask then, No, writeagain! is only for Wordpress.

Also If you are getting the feeds from a blogspot blog to a Wordpress Blog then WriteAgain! should work for sure.

If you are sure that the plugin is activated and still its not rewriting the posts, you must be using the Feedwordpress plugin to get RSS feeds...right? Now to get the problem solved, just click on "Enable Formatting" from inside the plugin settings and everything should be alright!