app/views/devise/confirmations/new.html.erb
<h2>Resend confirmation instructions</h2>
<%= form_for(resource, :as => resource_name, :url => confirmation_path(resource_name), :html => { :method => :post }) do |f| %>
<%= devise_error_messages! %>
<div><%= f.label :email %><br />
<%= f.email_field :email %></div>
<div><%= f.submit "Resend confirmation instructions" %></div>
<% end %>
<%= render :partial => "devise/shared/links" %>