Basically, it's a toast like "Cheers" or "Hey, It's been fun. Now let's get on with life. See ya."

The full sentence is "here's looking at you, kid" which I'd translate it as "(ขอให้)โชคดีนะ สาวน้อย"

I've never watched the film, but from many sources, I found that this might be the best way to translate it because although there's a hidden meaning behind, but you may need to keep it short.

You can follow the links here to find the hidden meaning which I think it's the best among many answers.

- Quote -

Rick was trying to find a nice way of saying "Hey. It's been fun. Now let's get on with life. See ya." It is a toast like 'here's to life' or 'here's to good health'. He is saying "Here's to the pleasure of just looking at you, seeing you in front of me". It is a poignant, bittersweet reference to the times they (Rick and Ilsa) spent together in the past and a (maybe subconscious) nod to the difficulties the future will hold for them.

- Unquote -

http://wiki.answers.com/Q/What_did_Humphrey_Bogart_mean_when...

If we refer to some story or some movies , there are some hidden meaning for looking. It could be " Wish you good luck" , "Wish you the best". Those are in positive word, but why I or someone can not use this for negative word such as : Here's looking on you , do not sheat me again. So, It could be positive or negative , why we have to follow their hidden meaning, just a movie which there is already known the story.