PSG are in control of the last-16 tie after February 18's first leg, in which Zlatan Ibrahimovic's double was sandwiched by an early goal from Blaise Matuidi and a late fourth by Yohan Cabaye.
Blanc, though, told the club's official website: "We prepare for every match to win, and that is the same concerning the match against Leverkusen.
"We respect this team. We have to back up our performance in the first game.
"We have been preparing for the match since Monday. It is down to us and we have to take the game seriously."
Ibrahimovic is set to be available but Matuidi is sidelined along with Marco Verratti and Gregory van der Wiel for the return leg.
"Zlatan, who has had problems with his back, is feeling much better," said Blanc.
"Marco, Gregory and Blaise will not play on Wednesday. The team which plays will be competitive but there will certainly be changes from the team which played against Bastia."
Leverkusen boss Sami Hyypia has also vowed that his team will give their all despite the lop-sided aggregate scoreline at the start of play.
"We are not writing off the game," he said, "Otherwise we might as well send the under-23 side.
"It's a great chance for the players to show up."
Midfielder Lars Bender is doubtful for the match but Omer Toprak and Stefan Reinartz are more likely to feature.
Hyypia said: "We are not taking any chances with Lars. I still have a little hope, but it will be difficult for Paris."