Nathalie Portman was offered this role
She turned it down because, as she later explained, her parents didn't want her first kiss to be with Jeremy Irons. I'm sure HE took the role though because he really WANTED to make out with a 15-year-old--it's called ACTING, you little jerk. Obviously, Portman has always been a classless a**hole who has no compunction insulting her fellow actors or roles she turned down, but she is a little more talented (and even prettier) than Dominique Swain. She still wouldn't have fit this role very well. HOWEVER. . .
She probably came close to looking like the "Lolita" of the beginning of the novel a few years earlier when she was in "Leon". A more sexualized version of that though would have been pretty creepy (although even as it was, I don't know why her parents found the "Leon" role totally acceptable, but didn't want her playing "Lolita" a couple years later). And unless they started filming the movie at the time of "Leon" and spent 4-5 years making it, she wouldn't have been believable as the older "Lolita" at the end.
On the other hand, if you want to imagine a sexy version of "Lolita". Tuesday Weld was apparently offered the Sue Lyon role (she would have been a little older than Sue Lyon--16 or 17 time). She turned the role down, she claimed, because she had already been Lolita in real life!
"Let be be finale of seem/ The only emperor is the Emperor of Ice Cream"