I have a 6 month old boxer that was diagnosed with kennel cough but doesn't seem to br getting better, she was very lively the first night after she was given a shot of antibiotics, but has been tfking them for 2 days and foesnt seem to be feeling better, she won't eat and when I let her out she seems to want to stay out, her cough isn't getting any better and is now not producing any phelm.. Anyone have any suggestions?

Kennel cough makes them feel pretty lousy and it can linger on for a few weeks.

Have you tried offering her soft food to encourage her to eat. Not eating is a vicious cycle, they don't want to eat so they skip a meal which in turn makes them feel even worse so they don't want to eat again and so on...

I would give it another couple of days (unless she declines drastically) before worrying too much.

You could also try a table spoon of honey. This works wonders on dogs AND humans who have a persistent cough. This may make her throat feel a bit better and inturn encourage her to eat.

Was she sent home with a cough suppressant? If not and the cough gets no better call and ask if they can prescribe her one. If she was, I would presume she was given something mild because that is what is typically done. One of my dogs would get kennel cough about once every couple years and we always had to pull out the big guns in order for him to get some relief. The milder form simply did not work for him.
As Shaz said give it a couple days, if she isn't better call her Vet and let them know. They may be able to prescribe something else for her.

Why isn't she taking the antibiotics? They are done, or you aren't giving them?
A lot of times we have to send our kennel cough dogs home with an antibiotic and a cough suppressant..