CADWorxP&ID tab: Utilities > Replace Block 
Utilities toolbar: Replace Block
P&ID menu: Accessory > Database > Replace Block
Command line: PIDREPLACEBLOCK
Replaces a block (symbol) with a new one. P&ID data is transferred from the old block to the new block. This command displays the Select Block (or Drawing) dialog box where you select a .dwg file containing the new block symbol.