It sounds like you're using the form_tag helpers (e.g. text_field_tag)
rather than the form helpers (e.g. text_field). The form helpers hook
into ActiveRecord objects and help you do this kind of redisplay
easily, but with the form_tag helpers you need to specify the values
For instance, if I have a text field like this:
then it will always render as empty when you reload the page, because
I'm not telling it what value to display.
However, if my controller picks up the data like this:
@name = params[:name]
then I can change the text field tag to this:
and it will use the contents of @name as the default value of the text
field when the page is loaded.