If you have applied for PR renewal through H&C, you should assume that expedite processing is not possible and your application will take longer to process since you don't meet the residency requirement and have requested H&C consideration.
If your PR card is expired, then you really have two options for entering Canada. The first is to apply for a PR Travel Document from outside of Canada. However this is not guaranteed to work if you don't meet the residency requirement. The other option is to fly to the US and then re-enter Canada through a land border using your expired PR card. Overall, if you are applying to renew your PR card under H&C, it's not recommended to leave Canada.