What are the consequences of replacing versus adding to an existing dataset in Amazon Personalize

I'm using Personalize to provide recommendations for my e-commerce application. The issue is items keep going out of stock and I'm constantly adding more items. Should I be adding to my data or replacing it each time? I'm wondering how replacing might affect the interactions data (i.e will they not be as useful because the replaced dataset will be considered brand new?)

Would love some advice from people who've used Personalize before on best practices.