Swansea secured a 3-0 win over the Spanish club in September but the Dane believes their opponents on Thursday will provide a trickier test
Laudrup's men secured a 3-0 victory over Valencia at the Mestalla in September, with Miroslav Djukic's side currently 11th in La Liga following defeat against Elche on Sunday.
Despite their mixed league form, Valencia have won three consecutive Group A fixtures to secure qualification for the knockout stages.
"When we played Valencia in Mestalla, it was in very special circumstances," he told reporters. "They had just had three defeats, but it changed just after we played them. They got back on track and won three or four games.
"Now, unfortunately, they have lost a couple of games in the last week, but I think it's different this time because they have already qualified.
"In Valencia, I think we played a great game, but we have to remember they played nearly 80 minutes with a player less. It would be nice to repeat it, but it won't be easy.
"My players all realise that it will be much more difficult to beat Valencia than it was in the first game."
Swansea could progress past the group stages prior to their game with Valencia, if St Gallen fail to beat Kuban Krasnodar in Russia.
Laudrup is not only keen to secure qualification, but also overhaul Valencia at the top of the group.
"I think we are in a very good position. Now we just have to finish it," he added.
"Whether you finish first or second in the group, the team you face (in the next round) is more or less of the same quality.
"Of course, there are a couple of teams that are really good sides, but, for me, the only difference is, if you are top of the group, you will play the second leg at home."
While Wayne Routledge, Michu and Garry Monk are ruled out of Thursday's fixture at the Liberty Stadium, Pablo Hernandez could make return from a thigh injury against his former club.