Are you able to give a little more information?
Why do you think they aren’t they re-ordering?
Are you only ranged in certain stores?
Is your product regarded as non-essential?
Do you have a major nationally branded competitor that is getting to supply?
You mention the “age of the product” is your item shelf-stable or perishable?
Are you exclusive to Countdown?
Depending on their reasons there could be some tactics you could use to get them engaged. Unfortunately, if it is a non-essential product the business will be focused on core needs but what you can position for is what happens once we move from Alert level 4 downwards.
Once I have some more information, happy to help here or contact me online at firstname.lastname@example.org