Houllier said: "Our vision and our goal is the Premiership, there's no doubt about that. But at the top level the age difference is a factor and in that respect we need a bit of time.
"Don't get me wrong, we have some experienced players in our squad but the average age of the team at Chelsea was just 25 compared to Chelsea's average age of 29. That makes a difference.
"Next season I want us to get back into the top three. That is the aim.
"I'm glad that we had to go through a bad period this season because the players have learnt a lot from it. It has been an average season and we can do better. I'm a great believer that you don't achieve anything in life without going through a bad period and this season has really tested us. We will be better for it next year."