How can I expedite the I-829 filing receipt since my CPR is expiring soon?

Everything has been slow but see if your check has been cashed as the file number may be on the back of that check-and follow-up with IPO, they will eventually reply.

The USCIS in general, and the IPO in particular, are experiencing unusual and significant delays in cashing and filing fee checks, and issuing receipt notices. It is unlikely that your I-829 has been lost, but if that happens, you will need to "recreate" the filing and provide proof that it was timely filed in the first place. If the I-829 is rejected, it will be returned to you by USPS mail and will contain a notice detailing the filing deficiency; you can discern what the issue is, correct it, and refile it as soon as possible. Otherwise, you just have to wait for the checks to be cashed and extension/receipts to be issued.

They are taking several weeks for receipts so your case is not unusual, which is why we stress to file 90 days before expiration, if at all possible. I don''t know of a way to expedite it.

There is no method by which one can expedite the issuance of the receipt notice. However, you remain a conditional permanent resident even without the receipt notice as evidence of this fact.

The USCIS has issued multiple notices that its mail rooms/processing facilities face a month-long backlog.

I am pretty sure they will not expedite your case. I am not aware of anyone who has successfully done that. You might consider applying to change from F-1 to tourist B-2 before your status expires. What does your own lawyer say?