First of all, the date your PR Card expires is merely the day you can no longer use it, it does not automatically affect your Permanent Residence status. You are a Permanent Resident of Canada until you voluntarily renounce your status or it is revoked. It can only be revoked after an investigation.
Staying outside of the country for such a long period of time and then renewing your PR Card is the main way that you can trigger an investigation. Even meeting the 730 day requirement is usually not enough to be met with the Residency Determination. We recommend spending at least an additional year in Canada.
The simple solution to your problem is to remain in Canada and not renew your PR Card until you are comfortably within the residence requirement.