The movie was released in 2008, but Barbara Pilavin died in 2005

I should state right off the bat that I have not seen The Onion Movie and don't know much about it, but purely going by its listed release year (2008), I am casually wondering how one of the actors, Barbara Pilavin, could have appeared in it given that she passed away in 2005?

I therefore suppose this movie, or at least part of it, was filmed years earlier. As that seems to be the likely case, does anyone know why The Onion Movie took so long to complete?

Thank you in advance for any info you may be kind enough to offer.