A tear in your down comforter should not indicate the end of its lifetime. In fact, depending on the size of the tear, you might be able to fix it to look rather acceptable. Avoid spending large amounts of money on a new down comforter when your old one has a simple tear in it. The problem might be solved by something as simple as ironing a patch to it.
Cut off all the loose-hanging and worn threads around the tear in your comforter with scissors.
Cut an iron-on patch to the dimensions of the tear. Cut it larger than the actual tear so it can bind with the comforter.
Set your iron to the cotton setting after plugging it in and filling it with water.
Set the comforter down on a hard surface, such as your floor.
Place a thin piece of cotton fabric on top of the comforter's tear and press the iron over the affected area, keeping it there for about six to 10 seconds. This preheats the tear to receive the patch much more readily.
Remove the fabric from the tear and place the iron-on patch directly on it with the adhesive side down.
Press the hot iron over the patch, keeping it there for about six to 10 seconds. Leave the patch alone to cool.