The Scottish champions have returned to pre-season training early as they start their preparations for next month's Champions League second qualifying round ties against Northern Ireland champions Cliftonville.
Ledley admits qualifying for Europe's premier competition is the main aim of the side next season as they look to emulate their success in reaching the last 16 of the Champions League last term.
Celtic are battling to keep the squad which performed such heroics in Europe last season intact, with clubs from England lining up moves for the likes of Victor Wanyama, Gary Hooper and Fraser Forster.
Wales ace Ledley believes their success last season was down to the team spirit in the squad and he hopes manager Neil Lennon can hang on to their in-demand stars and improve the team by bringing in some new faces.
"Our main aim is to qualify for Europe as we all enjoyed playing in the Champions League so much," Ledley told Sky Sports at an event to mark the unveiling of the club's new Nike kit.
"We all enjoyed playing in Europe last season in some fantastic games and we want the same again next season.
"Hopefully the gaffer can keep hold of our best players and bring players in to make us better.
"We know it is going to be difficult with the teams who we can play in the qualifying rounds.
"We need to be up for it and that is why we have come back early so we can be fit and ready for it."
Ledley is not surprised that the likes of Hooper and Wanyama have attracted interest from other clubs, but he hopes the club can secure their futures on new deals.
"Hopefully the club can sit down and speak to them, and show them we are moving forward as a club and keep them for a long time," added Ledley.
"There is always going to be interest in them because of how good they are as players and what they did last season.
"But the aim is to keep the squad together because we have got a good team bond at Celtic and hopefully we can keep that."
Celtic have already been busy in the transfer window, with striker Amido Balde and Dutch defender Virgil van Dijk arriving at Parkhead, and Ledley believes they will be valuable additions to the squad.
"I am looking forward to working with them and hopefully they will be good signings for us," continued Ledley.
"Balde looks like a good signing as he is big and strong and I think that is what we need as we don't really have a big man, and Van Dijk is highly rated in Holland, so it is good to see the gaffer is working hard to improve the squad."
Joe Ledley wears the new Nike Celtic Home Shirt for 2013/14. Paying homage to the club's legendary no. 7s, the kit is available from www.nike.com