You have stated that as on date the cheque in question has been presented twice and bounced. A notice has been issued. It is not stated whether the notice is for the first bounce or the second.
The time of 15 days to pay the amount represented by the cheque commences from the next day of receipt of notice. If not paid, the offence u/s138 is complete. Limitation for filing complaint, starts from the 16th day and lasts for a month.
If two notices have been issued, then limitation is from the first notice. Second notice does not extend limitation.
Non-receipt of the notice sent by post does not affect the complainant, if the same has been properly addressed to the address of the recipient last known to the complainant.
Assurances of payment within short time is always made by the drawers of cheques to the payees. If the complaint is not filed within limitation, based on such assurances and general aversion of people to avoid litigation, then precious time would be lost for ever. Remedy would lie, then to file a civil suit only, better under 37 of the code of civil procedure. But this would entail court fee, higher legal fees and time lag as civil courts are over-burdened with cases.
You can present the cheque any number of times within the validity period of six months from the date of the cheque (to be revised to 3 months, shortly) but since notice is already issued under sectiuon 138, limitation has already started running. So delay would only disable you from filing complaint.
Better to file complaint in time. If money is paid, then you can withdraw the complaint and end the matter.