Lampard, who will be 36 when the World Cup finals take place next year, is to captain England against Chile on Friday in the absence of Steve Gerrard and also to mark him hitting 100 caps.
Lampard is currently on a one-year deal with Chelsea, and he admits his future as a whole is yet to be decided.
"I'll be 36," Lampard, who will make his 103rd appearance for England on Friday, told the Sun.
"Right now, I'm not sure in my own head. At my age I understand it's not a four-year contract, it's a one-year extension. I'm more than happy with that.
"I'll make a decision after the World Cup... when we've won it and can all retire happy!"
Lampard admits that, despite taking the armband on Friday, he has a battle to make it to Brazil next summer.
"We're all in the same boat. What we've done up to now carries a bit of weight but if your form falls off in the next six months you can't expect to be going," he said.
"We all have to be on top form. If I walked around thinking my 103 caps would get me on the plane, I'd probably be on the beach. Because that means you're taking things for granted. I don't think any of us can afford to do that.
"Because of my age, it's always going to be a bit of a dogfight to get into the squad.
"I'm not silly. I understand that, no matter what age you are, you have to react. If you end up looking around at others wondering who's performing better, you take your eye off the ball.
"I also understand that at different parts of your career, you have different challenges. I'm very determined to show the manager that I can still do it regardless of age.
"He's always said it doesn't matter if you're 17 or 35, that he'll not look at you any differently. That's nice to hear. The rest is up to me."