[eluser]CroNiX[/eluser]
If you are using form validation, you must have a rule defined for each field or it won't repopulate because then the form helper won't know about it. For fields that don't "need" a rule, just pass it trim or something.
$this->form_validation->set_rules('field', 'my field name', 'trim');
Now it will repopulate normally using set_value.