Defoe came on for the final 24 minutes of England's 2-0 friendly defeat to Chile on Friday night to earn his 55th cap.
But he has struggled to secure a regular starting berth for Spurs this season, starting just one Premier League game this season, with manager Andre Villas-Boas preferring Roberto Soldado in attack.
Defoe has instead been limited to cup outings for Tottenham and it is his nine goals that have kept him in Hodgson's plans.
"Getting into a World Cup squad is based on merit and you have to play for your club," said Defoe.
"As a forward, if you are not getting the opportunities to play it will be difficult.
"It's important that everyone goes back to their clubs and plays games to try to impress the manager.
"It's a long way to go before the World Cup. There is a lot of football to be played and we will see what happens. You never know, I might play every game from now on."
As for the defeat to Chile, Defoe concedes the result was disappointing but backed Hodgson's decision to offer different players the chance to impress.
"It's not good losing, especially at home," added Defoe.
"You want that winning mentality going into a World Cup but there were spells where we did well and created some good chances, it could have been a different game had we put them away.
"Chile are a clever side but I suppose there are positives we can take out of the game.
"We were playing against a side who are technically good and kept the ball so well.
"But it was important for the manager to see other players and give them an opportunity to see what they can do at this level."