Can you please provide the model number of your fridge?
To my knowledge there is nothing that you can add to the system that will seal a leak in a fridge.
If the fridge has been leaking the leak will have to be found and repaired.
If it was left running with no refrigerant in it there is moisture in the system and it will have to be evacuated, a new dryer will have to be installed and the system recharged.
You would have to get a price from your servicer.
If the fridge is over 10 years old it is likely best to replace it. | 
Side by side refrigerator freezer 
I need to have my GE freezer recharged and leak sealer added. Does the leak sealer work as advertised and what is a fair price for this type of service? We would appreciate any info, Thanks,
