Q:

Form is sent only first time

I have a page to download a file depending on some configuration which is in a form. 
When I send the form, the file is downloaded fine, but if I change the form and send it again, nothing happens. 
Example form:
<form action="/download" method="get" target="_blank">
  <input type="checkbox" name="some_option" value="1" />
  <input type="submit" value="Download" />
</form>

The form is sent only the first time. 
I thought about using JS for sending the form, but I don't think the file download work that way. 
Any suggestion? 
EDIT: Added target="_blank" like suggested. 
UPDATE:
Added this:
$('form').submit(function() {
  this.action = addRandomParam(this.action);
  console.log(this.action);
});

The submit event is triggered every time the "Download" button is hit, but I still get the file downloaded only the first time. 

A:

Okay, the problem was some Javascript doing something like this (code merely illustrative :P) ...
$('form').submit(function() {
  if (alreadySent()) {
    this.preventDefault();
  }
  setAsSent();
});

This was to prevent normal forms from being sent multiple times. 
Thank you everyone for the answers.