Reliving old fir

An FIR was lodged in July 2012 against Mr. X in an Assam Police Station by a Mumbai based trader under Section 406 & 420 of the IPC, citing defrauding advance money given to X during the course of business. X acknowledged having received the payment and accordingly a compromise formula was suggested by the Police Station in-charge in Dec 2012, that X will pay 75% of the amount advanced to him and the complainant would withdraw the complaint or a compromise application will filed by the complainant; as the case may be. However, X didn't honour the commitment made by him in the police station and Mumbai based trader obviously couldn't afford to confront either X or the police station in-charge for obvious reason that sending man from Mumbai to Assam every now and then was not economically viable. Yet, in Dec 2014 the complainant wrote back to the police station registering FIR informing them of commitment made by the accused hadn't been honoured and they (the police station) should help the complainant recover the dues. There was no reply from the police station. In Oct 2018, somehow the accused being approached through email responded saying that the amount claimed by us is wrong in fact he had to incur certain expenditure out of the money advanced to him - thus effectively having acknowledged the receipt of amount. Can the FIR be relived/reopened? If yes, how? If no, can a fresh FIR be filed? If we go through court will the law of limitation bar filing suit for recovery of advance. The last acknowledgement, prior to the vague worded acknowledgement made in Oct 2018, was in Dec 2012 - but in presence of and in response to the FIR registered against him. Pl guide