Resizing pagination per_page on existing results

Is there an easy way to resize a pagination result? Effectively, I
want to have a dropdown on a results page that allows the user to
resize the number of results per page. Currently, I have something
like:

      @search_results_pages, @search_results = paginate(:products,
                                   :conditions => ["category_id = ?",
params[:category_id]],
                                   :per_page => 10)

Is there a way I can augment the per_page on existing results if I say
wanted to change the 10 per page to 25 per page?

Thanks,

Scott