When you update the pricing rules for products, these changes will apply to ONLY new products which you add to the Import List. These changes will not apply to the existing products in the Import List or any products already synced with your store.
However, if you want to the Pricing Rules to apply to products that have already been added to your Import / Sync List, you can use the "Price Lock" feature to resync. The price lock feature is located in your Import List under Pricing & Profit. See below.
The price lock is also located in the Sync List, see below.
Simply turn on the price lock and then turn it off and you will see your prices adjust according to your Pricing Rules.