Well, considering that they have already seen your file, and are aware of your IELTS expiring on Dec 13...it should be okay to give the exam again (at the earliest, of course)...I don't think there is any need to ask for an extension, cos they are already aware of your IELTS situation and have asked you to keep a valid IELTS ready for CIC submission....however, if it bothers you, keep them informed, so they can't hold it against you at a later stage...most of the time, they don't even acknowledge your mails...
And no, I have not got an ADR yet, nor have they acknowledged my mail informing them of my IELTS expiring, and second mail with the new IELTS score...
Most people have had the chance to update IELTS scores long before OINP started processing our Jan/Feb /MArch applications and some have even got nominated??
So, good luck...crack the IELTS neXt time...