seab said:
Yes I've been here for more than three months. I just want to know what documents I have to take to them. I'm currently on implied status as I wait for my post grad work permit to be extended.
I was in the same situation as you, and they told me I could not renew it while on implied status, as they had to see a valid work permit (or CoPR). That doesn't mean that what I was told was right - I went on implied status September 1 and got PPR later that same night, so I knew it wouldn't be long before I could sign up again. When I got CoPR and landed, I went back and they signed me up again.
As far as documents, take your old work permit, proof that you applied for the extension before it expired (I called CIC and they sent me an immediate email to that effect) and your passport. I brought all that, plus my expired OHIP card, but was turned down.
Let me know if your result is different from mine.