When you update the pricing rules for products, these changes will apply to all products which you add to the Import List and Sync List.
The exception to this rule is you have decided to turn off the Auto-price update. The Auto-price update will automatically keep pricing in sync with the supplier's pricing. If you choose to turn this off, it will be locked at the price which you have set and will not update, should the supplier make any changes.
When you update your Pricing Rules, they will be applied to all products which have the Auto-price update on.
You can opt to unlock all of your prices in bulk and reset the Auto-price update by going to the "Unlock all prices" section within the Pricing Rules page and selecting "Unlock all prices".
This will allow all of your products to be synced with the Pricing Rules, including any updates.