you have worked hard to get it going so, why not keep it that way.it doesn't hurt to fertilize every year.do a good soil test on it and this will let you know what it needs.the healthier you can keep it the better the deer will like it.if you have alot of deer pressure on your plots this will help it recover from heavey grazing.

Fertilizing every year is good but more important is lime. Plants can't utilize fertilizer and other nutients as well if the PH is not right. Lime is cheaper than fertiizer too!
Mike

All depends on your soil type, the type of plot you are planting, and whether or not you are harvesting the plot... Short answer is "No", but I would not chance it if I had a well established plot...

It depends on if you are removing your nutrients through your crop by mechanical or animal means. Harvesting a crop removes the nutrients removed from the soil. Deer eating leaves also removes these nutrients. If the plots were not utilized, then turn the crop under as green manure. Nutrients that are highly leached like N needs to be applied every year. P and K is usually put out in the fall or early spring for the following years crop in Production Ag due to the time it takes for them to become available.