Play It Again, Sam

HE'S a handsome American gambler in an exotic foreign city. There's a war going on, and he's fallen in love with a beautiful woman whose husband is mixed up in the intrigue. Will he stay neutral in the struggle or choose a side and commit himself? Will he go off with the woman, or will she end up with her husband? And most important, does all this sound awfully familiar? If so, it's because you remember ``Casablanca,'' where Humphrey Bogart went through the same adventures almost 50 years ago. ``Havana,'' the new Robert Redford movie, tries to freshen up the story, with a reasonable amount of success. But it's a pretty old bill of goods, and occasional doses of R-rated sex and violence aren't really what are needed to make it new.

Redford plays a poker hotshot named Jack Weil - as in ``jacks or better and the joker is wild,'' get it? He wants to set up his traveling game in Havana, where dictator Batista runs things. But some feisty rebels, including a guy named Castro out in the hills, want to throw him out and make big changes in their country. In the true ``Casablanca'' tradition, Jack doesn't want to get involved. Let the Cubans fight it out, he figures - it's all the same to him, as long as the cards keep coming up right.

But as Bogart learned in 1942, wars are hard things to avoid - not just physically but morally, as well. Jack meets a woman whose husband is in cahoots with the rebels. When this man is apparently killed, Jack falls in love with the widow, only to find that things aren't as they seem.

``Havana'' is a long movie - nearly two-and-a-half hours - and its mix of social, political, and romantic intrigue isn't enough to fill all that time. The movie also has problems transplanting a ``Casablanca''-type situation to a very different time and place. Rick, the hero played by Bogart, had the anti-Nazi resistance - obviously a virtuous group - to join forces with in the end. But the makers of ``Havana'' don't want to throw clear support to either Batista or Castro, so they dodge the political aspects of their story as adroitly as Jack does, depriving the movie of a solid and responsible center.

``Havana'' has its good points, though. Redford gives one of his most convincing performances ever; his face has never been very expressive, but age has given it a weathered look that helps his acting seem deep, if not profound. He also works well on this occasion with director Sydney Pollack, his collaborator on several earlier films. Here the two generate a fair amount of melodramatic momentum even though they don't get the screen really sizzling; the results are moderately effective, about midway between the excitement of their ``Three Days of the Condor'' and the dullness of their ``Out of Africa.''

As the woman in Jack's life, Lena Olin never works up a great deal of chemistry with Redford, but she remains a capable actress with a good mix of intelligence and charm. Raul Julia plays her husband with off-handed brilliance, although he's not on screen very long, and Alan Arkin - like Redford, an actor who gets better as he gets older - is in top form as a casino operator, a role that nicely complements his other current appearance in ``Edward Scissorhands.''

With talents like these on hand, ``Havana'' rarely gets dull. But it's no ``Casablanca,'' and this inevitable comparison is sure to work against it at the box office.