Retain model relationship with new dataset

Hello there,

I have a power bi file that takes in data from 4 excel files - Calendar, Product, Location, Sales, and Stocks along with some visuals. 

these tables are connected with Relationships. 

the Situation is I get a different dataset with the same excel file names, with this I would want to change the dataset but retails the relationships between them. how can I do that? 

whenever I remove the existing table and replace it with the new one, the relations are lost and I have to connect them back. 

EX: I remove the existing Products table and then upload a new Products table, the relationship is lost.