When you go on a vacation and you leave your cat behind there are some precautions you need to take. You need to make sure that depending on how long you will be gone for there will be someone there to check in on your cats, some cats may be self sufficient, but my cat is very needy and loving. If she goes too long without human contact she will become very sad, and so when vacationing without your cat make sure that you either pay someone or have a friend who is nice enough to come visit your cat and make sure that your cat's food is all right, water is all right and that the litter is okay; as well as the overall well being of your cat, making sure your cat is all happy and content.
Leaving something of yours, like a fluffy sweatshirt that she enjoys laying on or a snuggie so that she'll have something of yours while you are gone to remind her that you'll be back. Leaving your pet with some treats as well is a great thing to do, whether it is hiding the treats around the house or just putting them in the food bowl, it's also a good time to crack out some of that wet food, because while you are gone your pet is going to miss you and she deserves a treat for being such a good cat while you are gone.
Make sure you fill the litter box more so than usual, because since you won't be there to change out the litter she will need more litter as to avoid having to use other furniture to relief themselves on.
When you return home bring your cat back a gift of some sort even if it is just a treat or new toy!