While Mourinho knows he must continue to develop the existing talent in the squad, he concedes new faces are inevitable.
"It's clear in everybody that Chelsea next year wants to bring a striker," said Mourinho.
"It's also clear that we want to improve our players. I can't and I don't need to improve (Branislav) Ivanovic, (Gary) Cahill, John Terry.
"There are other guys I need to improve. I think we are doing that step by step, but it's not enough to be champions."