A movie would obviously be the quickest way to incite interest. Not only would that widen the fanbase, but it would also allow the books to go back in print. The problem with getting new fans is largely the fact that young fans can't get the books as readily as we could.
Unfortunately, who knows if there will ever be a movie (
) or a
high-quality tv series (a la Star Trek, SG, etc.)
So, until that miracle falls through it is up to us.
Unfortunately I think that some of the very nature of the Animorphs series will be a hindrance. A lot of newbies to the series, especially younger newbies, won't understand a lot of things: like the massive amounts of 90's references that made it so funny at times.