With two games remaining in Group F, PSG sit top by a point from Barcelona and have already booked their place in the last 16.
However, Blanc watched his side struggle against Ajax earlier in the group, when the Eredivisie side netted a late equaliser through Lasse Schone at the Amsterdam Arena.
PSG are much-improved since that draw, though, and Blanc expects the Ligue 1 side to show that in Tuesday's clash.
"We have improved a lot [since the last meeting], especially in our level of confidence," he said. "We still have to improve in our fitness and in how we play.
"Against Ajax, we'll play faithfully to our own philosophy, as usual, and I'm sure Ajax will too.
"But what we need to do is to have more of a killer instinct than we did in Amsterdam. If I remember correctly, we should have put the game to bed in the 47th minute. Let us hope we better convert our opportunities.
"We had plenty of problems in the first match. They were challenging, but we challenged them very much too."
Ajax cannot finish in the top two, but instead are in a straight battle with APOEL for third place, and a spot in the Europa League.
