When a refrigerator stops cooling, it's never a pleasant experience. Spoiled food can be worth hundreds of dollars and melted ice cream is no fun.
To keep your fridge cooling efficiently, don't block the vents with food, don't keep the doors open too long and make sure they close tight. Keep the temperature setting on the middle number. Set your fridge to 'humid' or turn the power saver option OFF if you do a lot of steamy cooking. Surge protectors can prevent an expensive repair on a computerized fridge.
There are many parts ensuring your refrigerator cools properly. Some of these parts may differ on different refrigerator designs. Each fridge has it's own fragile ecosystem that can get thrown off by a faulty part or warm air intrusion. A thorough inspection can identify the cause of the problem.