I think the ambiguity concerning whether Ilsa is really in love with Rick or with Laszlo is one of the elements that makes Casablanca such a timeless classic. Ingrid Bergman's performance convinced me that she was in love with both of them. Watch her in scenes with Paul Henreid (Laszlo) and you can see what looks like genuine adoration on her face. But the passion between Ilsa and Rick seems just as genuine. So, why couldn't she be truly in love with both of them? These are two very different men that she met at different times in her life, under very different circumstances. Even the kind of love she would have felt for the two men was different.
To answer your questions, yes I do think Ilsa is still in love with Rick at the end, but I don't think she's any less in love with Laszlo. Laszlo is probably (desperately) willing to believe that she isn't. "She did her best to convince me that she was still in love with me, but that was all over long ago" is a lie that both Rick and Ilsa are probably willing to live with so that they can both go on with their lives, and so that Ilsa at least can be happy.