There are no good options available to you and you should be prepared for the high possibility you will lose your PR status. You have two choices for trying to keep your PR status once you are ready to return to Canada in 3-5 years:
1) You can apply for a Travel Document based on humanitarian & compassionate needs and use your parents as a reason for not being able to return to Canada. In order for this to work, you will have to provide hard evidence to prove your parents were unable to live on their own (due to serious illness) and there was no other family member to take care of them in your home country. The evidence you provide should include things such as hospitalization records, doctors notes, etc. You should also ensure this evidence covers all of the years you were out of Canada. If you are simply taking care of your parents because they are elderly, this likely won't be accepted as a reason. If the Travel Document is refused, you can try appealing (although there probably won't be much point). If this is refused as well, your PR status will be gone.
2) Alternatively, you can obtain a US visitor visa, fly to the US and then try re-entering Canada by land using your COPR. For this to work, you will need to obtain BOTH a US visitor visa and a Canadian visitor visa for your two daughters. It's possible you may be reported at the border for failing to meet the residency requirement. If you are, you will have to appear in a hearing to argue why you should be allowed to keep your PR status. If you lose this hearing and any appeal, you will lose your PR status and be forced to leave Canada. If you are not reported at the border, then you will have to stay in Canada for two straight years without leaving for even one day to meet the residency requirement. Once you have lived in Canada for these two years, you will then be able to renew your PR card. If you don't already have a SIN, you should expect it may not be possible to get one and work during this two year period. It may also be difficult for you and your wife to get health care coverage. As for your daughters, you will not be able to sponsor them until you have lived in Canada for 2 years and meet the residency requirement. During this two year period, you should expect they will not have health care coverage and that it may be difficult for them to go to school.
