This might be helpul;
Remind Customers of Their Last Order (Shopify) | Klaviyo Community

Hi,
You should configure a Klaviyo flow triggered by "Placed Order." It would allow you to add elements of the original order into your email design. You can also utilize an event lookup in a show/hide block within Klaviyo templates....you can set up different product blocks based on specific groups or manually select products….it ensures the show or hide settings have been correctly configured (as it would be dependent on information from the said trigger event)

Replenishment flow is there for you.

Here’s the helping guide. Lemme know if you have any question

https://help.klaviyo.com/hc/en-us/articles/360003195232

Hi all, thanks for your feedback. I understand how to create the flow now. What i struggle with is creating a customized email for every customer. 

Example: A customer buys a specific product (lets say a protein powder). Now i want to send this customer a reminder to exactly purchase this protein powder again. Do i have to create a flow for every specific product or is there a possibility to for example create a flow for all products or a category such as protein powders and the system automatically knows which protein powder the customer purchased and sends him an email with the exact product? How could i add this to the email?

Regards,

Dennis