The Italian returned to GP2 after a year away, filling in for the departing Stefano Coletti, who left Coloni for Rapax.
Filippi, who finished second in the 2011 standings behind Romain Grosjean, then took an emotional victory on home soil in the opening race of the weekend, and Coloni has decided to retain him for the final round of the season in Singapore.
Team boss Paolo Coloni said: "After the win in Monza and the unrivalled pace we showed in both races, leaving Luca without a season wasn't even an option.
"Last weekend we immediately found the same amazing feeling we had in 2011."
Coloni added that Filippi's experience - he is the most experience driver in the history of GP2 with 109 starts – would be vital as the series makes its first visit to the Marina Bay street circuit.
"This [experience] will be very important in Singapore, as we will have very little time to learn and master the track," he said.
"I'm confident that we will be on the pace straight out of the box and that we'll end the season on a high."
The Singapore weekend will mark Coloni's farewell to GP2, as the Italian outfit will leave the championship at the end of the season.