Alter fields on add more I'm used Field collection to add content type as field with unlimited but i want to alter this form fields for adding #autocomplete_path on each field 
so i'm added the autocomplete for the first field as
 $form['field_1']['und']['0']['field_1']['und']['0']['value']['#autocomplete_path'] = 'admin/path/autocomplete';

when i add more field collection field i want to added the same autocomplete for the next fields 
any solution for this ?
Thanks in advance!.
After one day search i'm found solution in 
https://api.drupal.org/api/examples/form_example!form_example_tutorial.inc/function/form_example_tutorial_9/7 
this example adds default values so that when the form is rebuilt, the form will by default have the previously-entered values.