At this stage last season, Inter had won five of six games and were top of Serie A, but they are currently fourth in the standings after dropping seven points, while they drew 0-0 at Manchester City in their opening Champions League game.
"It's difficult to win (the title) and it's even more difficult to win again. But as far as the lads are concerned, they are working with great commitment," Inzaghi told reporters on Monday ahead of Red Star's visit.
"Then, of course, we still lack that continuity that we had, especially last year. That continuity that makes the difference to you both in the championship and in the Champions League."
Finding continuity will be even more important in this season's Champions League with the new league phase format.
"Last year after the first two games you were able to take stock and understand how the games could go, because then you knew that in the third and fourth game, you would have played the same opponent, home and away," Inzaghi said.
"Now it's a bit of everyone against everyone. It's a winning formula with two extra games, with more difficulties. You can't make calculations, because it's a sort of one-off game."
Those extra European games mean that rotating his team will be of even more importance this season, and Inzaghi is still unsure about who will start up front against Red Star.
"I still have to decide between Lautaro (Martinez), (Marcus) Thuram, (Marko) Arnautovic and (Mehdi) Taremi," he said.
"They will probably have a good chance to play all four of them. I don't know who will start, tomorrow I will have to evaluate today's training."
Piotr Zielinski has yet to start a league game this season, but Inzaghi confirmed the midfielder will be in the lineup against the Serbian side and expects a tough challenge against an outfit who lost their opening league phase game to Benfica.
"It's a team that started on July 20th. They've had nine league games. They've played in the preliminaries," Inzaghi said. "It's a very well-trained team, with excellent players."