Basically the time limit prescribed in the CrPC only to secure the freedom of the a person so that, if any case is made out, the charge sheet be filed against that person so that the court take cognizance or otherwise set free the person.
However, the limit to file the charge sheet remain same described in section 167 (2), the police can apply for extension and it is discrition of the Magistrate to allow the period as he deemed fit.
Further, chapter XXVI deal with the limitation for taking the cognizance. Section 468 of CrPC contemplated the period to take the cognizance by the court :-
01. Six months, if the offense is punisable with fine only
02. one year, if the offense is punisable with imprisonment for a term not exceeding one year.
03. Three years, if the offense is punisable with imprisonment for a term exceeding one year but not exceeding three years.
for the purpose of this section the period of limitation, in relation to offense which may be tried together, shall be determined with reference to the offense which is punishable with the more severe punishment or, as the case may be, the most severe punishment
Therefore, in your case the limitation to take the cognizance is 7 year from the date offense as contemplated in section 469 CrpC