Exustar road pedals are compatible with Look cleats, so you need to make sure any new shoes you consider are also compatible with Look cleats. Luckily, shoes w/ Look compatibility are very common, but you will want to check specifically when downselecting which ones you want to buy.
Generally, when you buy new shoes, you should buy new cleats; old cleats which are worn or stressed may crack and cause, at best, an unhappy ride home or, at worst, a crash. If this is not your style (for philosophical or monetary reasons), be sure to inspect the old cleats very carefully or, better, have your Local Bike Shop (LBS) mechanics check'em out.
One consideration when buying new cleats is float; this is how much your heels can move side-to-side without unclipping, and is designed to reduce stress on / fatigue of your knees. Look cleats come with three levels of float: none; 4.5 deg. or 9 deg. Non-Look cleats may have different float ranges. Which is best for you is a personal decision, based on riding style, experience, fitness, physical structure, etc.
Another consideration is the type of Look cleat: the "old" / non-Keo version (Delta?) or the Keo-version. These are not compatible, so be sure to understand which you need. If you are not sure which you have, take your old shoes with you when shopping for new cleats.
The last issue you'll have to deal with is installation; mounting the cleats is easy, but positioning can be very touchy. Here again, unless you have a lot of experience, I would recommend asking your LBS to assist in this; it may cost a little bit, but it should make your riding experience much better.
A few resources which may help in your efforts:
Hope this helps.