clear a form after an ajax create

I'm just starting to play with rjs, I have an index page with a remote_form_for to create new items. That's working. However, after the ajax updates my container, the input form needs to be cleared. I'm not sure how to do that

http://pastie.caboo.se/75318

tia

linoj

thank you, yes, I realize the empty Choice object is not correct, that
is my question. I'm looking for suggestion how to clear the form
fields from the rjs.

The _form.html.erb is quite simple

<p>
  <b>Prompt</b><br />
  <%= form.text_field :prompt %>
</p>