Wow, I am surprised that all of your answers so far have been to replace it. My suggestion would be to fix it. Generally Whirlpool appliances are good appliances and can be repaired. My house was built in the 50s and still has the original appliances in the kitchen. My oven (electric) recently stopped working and we called a repairman. He replaced a wire for us. The parts to fix the oven were less than $3 and he at my house less than an hour. Our total was less then $40 to fix it. I can't guarantee that your costs would be as low, but it is worth a shot. It shouldn't cost you much for them to come out and tell you what the problem is so that you can make an educated decision. We recently fixed our dryer and the cost for the part was pretty high, but it was still less than buying a new dryer and, in my opinion, better for the environment than buying a new dryer.
If you find a good repairman (I would suggest checking Angie's List) chances are good that your stove can be fixed.
Also, with the post about efficiency, I don't know much about efficiency in gas stoves, but gas is cheap currently and you don't hear much about the energy efficiency of stoves, so I can't imagine you would make up the cost of a new stove quickly. Plus, the environmental damage done by trashing your current stove and done by making and shipping the new stove is pretty high. Here is a pretty good article about when to replace vs. repair, but there are no details about stoves: http://www.revisionarch.com/Library/Repair%20or%20Replace... I think the advice I have seen most often is: If the repair will cost more than half the price of a new, more efficient model, it may be time to do some shopping.
Good luck.