In what possible sense has AIMA replaced PAIP? PAIP is crammed to the gills with substantial pieces of Lisp code that do interesting and useful things; it focuses as much on the "programming" as on the "artificial intelligence" and has a lot specifically about Lisp. AIMA has code snippets but not much more, and actually they're generally (always? I forget) pseudocode, not actual code in Lisp or any other language.

AIMA is a fine book. PAIP is a fine book. I don't see how you could possibly use either of them to replace the other.