Plastic liners are used in a number of different products, but where you will most likely to see them is inside of a fridge or freezer. Plastic liners are designed to last as long as the fridge or freezer itself. However if the plastic liner does become damaged, you can repair it using a plastic repair kit and a food grade silicone sealant. Once repaired, the liner will be as good as new and should continue to function until you are ready to replace the entire fridge.
Unplug your fridge and store the food in coolers or a second fridge if you have one. Leave the fridge door open and allow the plastic liner to warm to room temperature.
Install a small drill bit, 1/16th or smaller into a power drill. Drill two small holes, one at each end of the crack. Doing this will prevent the crack from spreading any further.
Run a bead of food grade silicone sealant along the crack and the two small holes. Follow the instructions on the silicone packaging for mixing, if required, and for the length of time needed for the silicone to cure.
Cover the silicone sealant with a liner repair kit that is designed for your brand and model of fridge. After the required time for the repair kit to dry, plug the fridge in, allow it cool then replace the food back into the fridge.