Will sperm cells exhibit chemotaxis towards sucrose?
If you google "sperm chemotaxis sucrose" you learn some things of interest. Notably, wikipedia's article on sperm chemotaxis indicates that the important chemoattractants for sperm (the things that attract sperm via chemotaxis) are various signaling molecules given off the by the egg. 

It is not clear why you would necessarily think that sucrose would attract sperm or that salt would repel them. In the first case (sucrose), it is not obvious why sperm would expect to see sucrose. If I remember correctly, sucrose is actually pretty rare in animal physiology except as an energy source in plants that animals eat; and sucrose is largely broken down into monosaccharides before it even leaves the small intestine, so it's not like it's circulating in the body. For instance, a lab protocol for studying animal sperm chemotaxis suggests adding sucrose as a densifying agent that doesn't interfere with chemotaxis, suggesting that sperm are pretty independent of sucrose. In the second case (salt), it is not obvious that sperm would necessarily avoid the things that kill them. Those things may be correlated with doing their job! Most sperm cells are expected to die in the human reproductive strategy.

In plain terms: there are huge numbers of sperm which are competing really hard with each other to find and fertilize an egg, not to find sucrose or to avoid salt. The chemotaxis that sperm exhibit will tend to help them accomplish this goal. So it seems (according to wikipedia) that they follow the signals that say 'egg', not the ones that say 'sugar'. 

Update:
Sorry, only just saw update on Q. Thanks for the clarification- sounds like fun! I've been curious about the foldscopes.

If what you want is to do an experiment, then I think you've actually got a great start with knowing first that salt interferes with their motility. That is a control experiment, e.g. the very first thing you should do, to make sure that the world works the way other people say it should. (First rule of experimental science: never trust anyone!). Look up a protocol which suggests a sperm-inhibitory concentration of salt (ideally kosher salt, not table salt which has a bunch of other stuff like iodine in it). Put sperm in that concentration of salt and then also in a medium where they should show chemotaxis (the protocol I linked to could be helpful here). See if you can reproduce the salt inhibition, ideally in a medium that is otherwise identical to the medium that allows chemotaxis.

Next, try other stuff. Unfortunately, chemoattractants are probably proteins/small molecules you can't buy at the supermarket. But you could try to get creative. I can't ethically recommend that you try to find a human source, because that gets weird pretty quick, though it is the obvious suggestion (I assume you are talking about human sperm). Potentially there is an animal source for such things which isn't too expensive. 

However, you could say to hell with chemoattractants and chemotaxis, and try to just understand sperm motility. You could try other osmotic shocks, with simple cheap chemicals like glycine. It looks like there is some literature that calcium ions affect sperm motility. Or you could play with pH, using vinegar or lye, or temperature. I bet that all of those affect sperm motility (probably for the worse). Or you could try the effects of various weird hippie herbs from the health food store. It sounds like you are just looking for an easy, fun experiment, and if that's your goal then I suggest you try a bunch of things and see what happens. That way you're more likely to find something interesting. 

If what you want is a more elaborate experiment, then I think it is worth your time to sit down and try to read up on how sperm work, and then design an experiment that really clearly tests a hypothesis. I am not an expert here, but the Yoshida article I link to looks like it has a good literature review.

Hope that helps.