The Cottagers defeated Bolton 3-0 on Saturday.
Dempsey said: "I hadn't got too many goals away from home this season.
"It is good to add to that and good for us to get three points away from home. We are excited about that, we can add to that.
"I have never got these type of numbers before - 21 for the season, 15 for the league.
"I am happy with that return and we have still got some games left, so hopefully I can chip in with a few more."