Pathankot was targeted as forces tightened grip in J&K:

Security forces have tightened their grip in Jammu & Kashmir, forcing terrorists to shift elsewhere, Defence Minister Manohar Parrikar told Lok Sabha today, claiming that this was the reason for attack on Pathankot Airbase.
"Why have terrorists shifted towards Punjab? There is one reason. It is because the security forces have tightened their grip in Jammu & Kashmir," he said while intervening in a debate on Pathankot attack of January.
He was responding when a member asked why Punjab had been chosen as a target by the terrorists.
According to Parrikar, security forces in Jammu & Kashmir have turned on the heat on terrorists as a result of which they are trying to "shift down wards".

He said in Jammu and Kashmir, 104 terrorists were neutralised while only 31 security forces were killed in 2014.
"...Earlier the ratio used to be 1:1 almost. Now, ratio has shifted in favour of security forces to 3:1. In 2015, it was 97 and 33," the Minister said.