Some products are just not replenished at a rate that would make a replenishment email campaign worthwhile, however, If you're in the business of selling goods that "get used up" frequently, then it's likely that your customers will need to re-order those items before they run out.
If your business involves selling items in any of the following categories, then a Replenishment Email campaign is perfect for increasing the LTV of each customer:
Fresh Food, Drinks and Groceries
Beauty and Personal Care
Socks and Undergarments/Underwear
Vitamins and Supplements