Limitation

limitaion for filing is 3 years, but incase u hav received any payment or installment or interest than the limitaion will again start from that day.  
 

Limitation may be reset as suggested by Mr.Rama chary.

In the absence of specific loan period, limitation is for 3 years any apportioned payment will definitely going to weakned your case,so best way is to sort it out through mediation.

If matter can be resolved amicably, by mediation then nothing like it.

Since, you received part-payment in February, 2016 the limitation clock is reset. As of today, the limitation period end on January of 2019.
Hence, you can file a Summary Civil Suit under Order 37 of the Code of Civil Procedure, 1908 at the local district court.

You can also file criminal case under Section 406 and Section 420 of the Indian Penal Code for criminal breach of trust and cheating.
As per law, you can proceed against a debtor via civil suit and criminal proceeding simultaneously.

In Iqbal Singh Marwah and Anr. Vs. Meenakshi Marwah and Anr. [AIR 2005 SC 2119], Hon'ble Supreme Court observed that both civil and criminal proceedings in respect of an incident can go ahead simultaneously. There is neither any statutory provision nor any legal principle that the findings recorded in one proceeding may be treated as final or binding in the other, as both the cases are to be decided on the basis of the evidence adduced therein.

Similarly, in the case of P. Swaroopa Rani Vs. M. Hari Narayana @ Hari Babu [AIR 2008 SC 1884] Hon'ble Supreme Court observed that criminal proceedings and civil proceedings can proceed simultaneously and there was no statutory bar on two proceedings being conducted simultaneously.

All the Best.