Actually, if at all possible, this is the best method, especially if most of your lawn is in pretty good shape. Do whatever you can to avoid reaching the need for either a renovation or reestablishment. Repair is fixing only those areas that need it, and giving the entire lawn a good dose of tender loving care with some fertilizer and weed controls (follow label directions-better yet, hire a pro to put you on a regular fertilization and weed control schedule-that way, it won't get so bad and in time, you'll have a lawn that you won't be embarrassed to have people talking about.
The important thing in repairing a lawn is to match the new, with what you already have in place so it's a nice blend. For example, you live in the north and you have a blend of Kentucky bluegrass (very common) and you've got a few dead spots that didn't green-up this past spring, you'll want to plant more Kentucky bluegrass blend. Don't put in tall turf type fescue because you heard it's really great (which it is). They are two different types of grass that shouldn't be mixed.
Now, if the bad areas are small (probably where Fluffy took care of business all winter long), areas less than a foot in diameter), ignore them, they'll fill by themselves in a month or so. Larger than a foot and then it's time to take some action.
Step One: remove the old dead areas with a shovel. Trim up the sides of the area being removed so they're straight. Fill in the area with new top soil, so the new is level with the old. Now plant your seed (follow label directions). In the south, put in matching sprigs or plugs. For seeds, you can cover with some straw, which is good for areas that might be damaged by a heavy rain. Otherwise, just a little peat moss on top will work just fine.
When planting the seeds, don't bury them in the ground. Use just enough top soil to barely cover the seeds (no more than ¼", with less being preferable). After covering, press down on the dry soil with the back of a hoe, or use your shoe and lightly tamp it down, but don't stomp on it.
Options: There are some products out there that combine a few steps and make it a little easier. Scotts PatchMaster contains just about everything you need: seed at a predetermined rate, fertilizer, and mulch to help keep the seeds properly moist. This works great if you happen to have the same grass type as the package. If not, then don't use it.
Another option is if you can find sod that matches your lawn, you can quickly repair the damaged areas. Follow all of the directions up to the point of planting seed, except for the added top soil. Only add enough topsoil so that with the sod, it matches your existing level. Sod takes about 2 weeks to get established. Keep it watered and don't let it dry out during those first 2 weeks.
Step Two: Apply a fertilizer over the area (follow label directions) that is specifically designated as a "starter fertilizer."
Step Three: Keep the soil moist. For seeds, only the top surface needs to stay moist, but (and this is important, especially if the weather turns hot) it can't be let to dry out completely, particularly in the last half of the first 2 weeks after planting. Once the seeds germinate, keep the soil evenly moist and increase the amount of water, but cut back on the number of times you water. In other words, keep the soil moist at a deeper level (moist-not wet!).
Step Four: In a few weeks things will start to pop. If possible, don't walk on the areas, and don't mow the areas until the seeds are about 2" — 3" tall, about 3 weeks after the seeds first germinate. Then you can forget about it and just treat it like the rest of the area. Don't use any weed controls on the new grass for a couple of months until it gets really established and hardened off.