The 35-year-old midfielder, who became Chelsea's all-time record goal scorer last season, recently signed a one-year contract extension.
Lampard was a vital player in Mourinho's first spell at Chelsea, and he remains part of the manager's plans for the forthcoming campaign.
Mourinho said: "I believe he is the same player, with the difference of, he is 35 and the time to recover from match to match is not the same for a man of 25 to a man of 35.
"The role doesn't have to change. What has to change is the way we analyse competition. Before we didn't analyse, before it was 'every match: he plays'.
"Sometimes I wanted to give him a rest in a Carling Cup match and he said 'if you give me a rest the next match I will not be the same, because I have to play every three days'.
"He can't play 60 matches like he did before, but the quality of the player and what he represents for the way I like to play football is exactly the same."
Mourinho maintains that he will not let factors such as age or nationality come into his thinking when he is selecting his best XI.
He said: "Performance is how good you are, not your passport or birth certificate. It's about performance, nothing else."