A standard recipe of 4 servings uses 5 cups liquid (wine, broth, water, etc.) to 1 1/2 cups arborio rice.

Prepare your risotto according to your recipe, but use only 3 1/4 cups liquid (reserving the remaining 1 3/4 cups for when you are ready to finish the risotto). Cook on medium-low heat for 16 minutes only according to your recipe.

After 16 minutes, remove the rice from the heat. If you are going to use it within the hour, just slid it to the back of the stove, no heat, and let it sit. If you are making well in advance, place in a shallow baking pan and cover. Refrigerate until ready to serve. The rice can be prepared to this point up to 3 days in advance.
 

When Ready To Serve:

Remove chilled rice from refrigerator and bring to room temperature. Place the remaining 1 3/4 cups liquid in a wide pot or saute pan; heat to a simmer over medium-high heat. Reduce heat to medium and add the partially cooked risotto. Stir with a wooden spoon until the liquid is absorbed and the rice is done cooking, approximately 4 to 5 minutes or until rice is tender but still firm (the rice is done when it is tender, but firm to the bite). Turn off the heat and immediately add the remaining butter and Parmesan cheese, stirring vigorously to combine with the rice. Add salt and pepper to taste.

NOTE: To test the risotto for proper consistency, spoon a little into a bowl and shake it lightly from side to side. The risotto should spread out very gently of its own accord. If the rice just stands still, it's too dry, so add a little more stock. If a puddle of liquid forms around the rice, you've added too much stock. Spoon some liquid off, or just let the risotto sit for a few more seconds off the heat to absorb the excess stock.