If you have added line items from your price books onto a favourite, then the standard pricing for them will update with changes to that price book item.
For example, if I add a line item from my custom price book into a favourite, then change that item's cost price when editing my custom price book the favourite will also update to use that new price.
In a similar vein, if I upload a new price file CSV from a supplier, then the standard pricing will also update for any of those line items in the favourites as well.
However, there is one situation to note: Line items that have an override or otherwise non-retail rule for their sell price in Tiered Pricing will still use that override or rule instead where that pricing tier is used.