title: Explicitly re-register device to GCM
body: <p>Is there something wrong in the fact that every time I log in to my android application, the first thing I do is to register to GCM.
  I know it's not necessary to do this, but in order to check if the registration id is refreshed to a new one or it s still the same, I plan to re-register.</p>
  
  <pre><code>final String regId = GCMRegistrar.getRegistrationId(this);
  if (regId.equals("")) {
    GCMRegistrar.register(this, SENDER_ID);
  } else {
    Log.v(TAG, "Already registered");
  }
  </code></pre>
  
  <p>I would also like to know if by re-registering to GCM I am somehow forcing the registrationID to expire.</p>
  
  <p>Thank you!!!</p>