The Replace function is accessible within a Project Editor via the Tools tab:
This feature is essentially a "delete/add" function but with the added benefits of maintaining some of the original Item's information.
Once you have selected the Item(s) that you want replace, click the Replace button and choose either Product, Labor, or Package:
This will open the following form:
Choose a replacement item from your Catalog or if necessary you can create a new Product:
You have multiple options for maintaining some characteristics of the item that you are replacing:
If you are doing the Replace within the Visio or AutoCAD file open you will have an additional option to "Maintain Shapes"/"Maintain Blocks":
Click [Replace and Close].