The Perth striker scored a hat-trick in the 7-0 Bettered Cup win over Brechin City at the weekend to take his tally for the season to four.
The 27-year-old attacker has been unable to reach the heights of his first spell at McDiarmid Park where he peaked with 27 goals in 49 appearances in all competitions in 2013/14 before spells at Sheffield Wednesday, Preston and Aberdeen.
Davidson, preparing for the trip to Hamilton on Saturday, believes the Scotland cap needs to focus only on scoring.
He said: "I remember watching him when he went down the road to England and he did a lot of unselfish work, a lot of work outside the box.
"He needs to get back to being a little bit more selfish and make sure he saves his energy for basically scoring goals.
"Down the road he ended up being a workhorse, doing all the work and the other guy got to tap the ball in the net.
"We need to get him back to that kind of mentality, of playing within the box, not drifting too wide at times because he's the one that will ultimately get the goals.
"I can see signs his movement is back, the way he spins and gets behind. He's got to get back to the habit of just shooting all the time.
"When he played at that time (2013/14) he got half a yard and just hit it. We need to get that habit back into him."