Raul scored 15 goals for Schalke last season before leaving this summer and no new forward has been brought in to replace him.
Instead, Stevens says his defenders must now take on more responsibility.
"Of course we miss those goals that Raul scored, but we can compensate for that by conceding fewer," he said.
"We conceded 44 last season and that is far too much for a top team."
Stevens could hardly ask for striker Klaas Jan Huntelaar to take on Raul's goals considering he was already the Bundesliga's top goalscorer with 29 strikes last term, but that feat no longer counts anyway, according to the Dutch coach.
"Finishing third in the league and qualifying for the group stages of the Champions League was super, but that is in the past," he said.
"We start off from scratch again."
Hannover have a small advantage in that their season is already four games old - three in the UEFA Europa League and one in the DFB-Pokal last weekend.
"They are already in a rhythm," added Stevens. "But all that does not matter anyway - we need to focus on ourselves."
Stevens is likely to be without Benedikt Howedes and Jefferson Farfan while Timo Hildebrand is expected to get the nod to start in goal ahead of Lars Unnerstall.
Hannover coach Mirko Slomka led Schalke to the quarter-finals of the Champions League in 2005 and knows how high the expectations are at his former club.
"I can see them being up there again this season," he said. "Schalke will be fighting for a place in the Champions League so our guests are favourites for this game and we certainly respect them."
However, Hannover also have lofty ambitions having qualified for the Europa League two years in a row.
"We also have a lot of quality and therefore we have a good chance of winning this game," said Slomka on his club's website.
"I am glad we have already played so many competitive matches because that is the only way to get into a rhythm and work on our errors, but I have already seen lots of positives."
Slomka has Christian Schulz back in his side, but Mame Diouf is still out.