First thing to do is to get her a trim. It will remove all of the dead ends.
Next, buy some product:
1. A good conditioner for damaged hair. Tell her to use it after she shampoos and to let it sit for a minute or two before rinsing. As for shampoo, get a moisturizing one. No need to spend a lot on any of these products.
2. I suggest an argan oil. Use it on her wet hair after her shower.
3. A leave in conditioner. Fructis makes a good one.
4. A very wide-tooth comb
5. No snag elastics.
Doesn't matter if my daughter's hair is up or down. The chlorine is so rough on it. I use the leave in conditioner in the AM before camp.
Also, the best thing she can do for her hair is to wet it with clean water before jumping in the pool. Her hair will absorb the clean water and not the chlorine.
Good luck!!