Lennon expects another summer of change at Parkhead, although he is not sure how many players will leave.
And he accepts that they now face more competition in the transfer market as they look to unearth another "gem".
Celtic sold Victor Wanyama, Gary Hooper and Kelvin Wilson last summer and Lennon is unsure whether there will be any less upheaval this year.
He told fifa.com: "I think there will be suitors for a couple of our big players, and one or two are coming out of contract, so you'd have to expect they'll be leaving.
"Realistically, I think we have to expect another decent turnaround, with a few players going out and few coming in."
Lennon has already admitted he expects goalkeeper Fraser Forster to attract attention in the summer while out-of-contract Georgios Samaras is set to move on.
Israeli midfielder Beram Kayal told a newspaper in his homeland that he might be sold with a year left on his deal and the agent of Dutch defender Virgil van Dijk has spoken about a potential move. Tom Rogic and Tony Watt have also been loaned out for spells this season.
Lennon added: "Bids are all but inevitable for a couple of our players; it's just whether we accept them or not.
"But everyone has their price and we're preparing with that in mind, looking at other options for the positions concerned."
Selling Van Dijk and Forster would bank Celtic a healthy profit, which they made with their three sales last year.
But the likes of Teemu Pukki, Derk Boerrigter and Amido Balde have struggled to make a major impact and Lennon admits signing younger players from abroad is always something of a gamble.
"We're already looking at a few players we like, and with the league now settled, it gives me the space to go out myself and look at a few who are under consideration," he said.
"But whether we can keep on unearthing little gems, or big gems, is another matter.
"Our strategy has worked on the whole, but other clubs are now looking at our model and trying to copy it.
"And you can't always get your signings right. You just hope that your record of good ones outweighs the bad because it's such a crucial part of the job."