The problem with urine on the lawn is that it contains urea, which has the same effect as dousing the lawn with too much nitrogen. You can, if you don't mind the effort, apply water right after the deed to dilute it, but you may wind up with green, lush patches of grass that stand out from the rest of the lawn.
In the long run, the easiest solution is to establish an out-of-the-way area for a doggie bathroom. This will take some work to get the dog trained to using that area exclusively, e.g., a week or two being taken out on a leash and directed to the area and rewarded hansomely immediately afterwards.
Here's more details from the University of Minnesota Extension Service: