Workflow sedn email due date even after change date

Hi,
I must create a couple of Work-flows, which will be send notification to user (something like remainder).

I have created first WF that will be activated when item will be created or modify (sharePoint Online 2013).

WF-1
If State = New or Offer send and Email has not been sent then, pause until DeadlineDay = Today --> send email and change state to EmailHasBeenSent.

It's working fine, but if user will change the Deadline date The new WF will be created (maybe) and previously WF are still working. I don't know how to stop this WF.

Example:
Deadline = 25.09.2013 WF will set this date to send email. If I change date to Deadline = 30.09.2013 Email will be sent on 25.09.2013.

How can I do WF that will be check every day is the date has been change?

I try this:
http://social.msdn.microsoft.com/Forums/sharepoint/en-US/aeaba6e9-1d13-4876-b012-53d32324909e/send-email-if-todaydue-date

and

http://sharepoint.stackexchange.com/questions/61823/how-to-send-mail-every-quarter-till-expiry-date-using-sharepoint-designer-workfl

Second WF if similar but send email two days before Deadline -> 2DaysBeforeDedline.

Can you help mi with design this WF (step-by-step)?