Frank Lampard confident of Chelsea revival after dismal season
Chelsea, 12th in the standings with 43 points, play fourth-placed Manchester United, who are bidding to secure a Champions League place, on Thursday.
Chelsea, who won the Champions League in 2021, will end this season without silverware despite their new US owners' huge spending on new players.
"There is a lot to go over to get to the bottom of it. The club has to explore every factor and make sure it does not happen again," Lampard told reporters.
"It could be a long process - from my experience, when you switch something off, it isn't easy to switch on again."
Lampard is optimistic, however, that Chelsea have the right structures in place.
"When you look at the good models around that have consistency in those areas and decision-making and how the club moves forward, they're generally more successful clubs," Lampard said.
"Where we are at the minute, that will be the work process to try and see where are we aligned, where do we want to get to and what does it look like."
Lampard, who will step down from his role as temporary manager at the end of the campaign, urged his players to show fighting spirit against United.
"They (players) have to show there is something resting on this game in terms of their personal and collective approach," Lampard said.
"We have to go with a very good mentality against a good team who are fighting for something we have had for many years - and now we don't have it."
Lampard said that forward Joao Felix (23) would be back after missing the defeat at Manchester City but French defender Benoit Badiashile's (22) will be out for "months rather than weeks".
Chelsea forward Raheem Sterling (28), who is capped 82 times, was left out of England's squad for next month's Euro 2024 qualifiers.
"Raheem is a top-level player... I know sometimes these games at the end of the season are different challenges compared to individuals who have played a lot of games," Lampard said.
"So, if there's a mutual conversation between the two (Sterling and England coach Gareth Southgate) then I'm sure they will find the right outcome - best for England, best for Raheem."