I assume you already have your SIN since 5 years ago, if you didn't, take care of that now and apply for your health care and drivers license as well before your PR card expires. Then sit tight for 2 years and wait until you meet the residency requirements again.
You will not be able to travel outside Canada because you will not be able to come back without a PR card but you can work and do everything else. Your PR status will not be questioned as long as you stay in Canada unless you apply to renew your card. Once you have your 2 years, you can apply to renew your card. They can not go further back than the 5 years before you apply. As you have 2 out of 5 years in Canada when you apply to renew, they will have to renew. If you apply to renew now, you will lose your PR.