I see your point and I think the English version, "laugh more, live more" could be either, grammatically speaking; the use of ellipsis points or exclamation marks would have removed any ambiguityI don't see "laugh more, live more" or "laugh more, live longer" as imperatives either. To my mind, the bracketed words are implied: "[if you] laugh more, [you will] live more / longer."
I like this a lot - I will say, however, that it sounds like billboard writing or a proverb. As to whether laugh more, live more or laugh more, live longer or the more your laugh, the more you'll live is more appropriate, I think it depends on how and where the phrase will be used."laugh more, live more"