Is this netlist flow or an integrated PADS project? If your parts are defined correctly you can use the 'slot' command in PADS DX Designer/xDX Designer to swap the parts. To get the command window open press the 'space bar' on the keyboard. Select the resistor and then type 'slot' in the command window, in the dialog that pops up choose the slot you want.
if you are using the PADS integrated flow with a central library then use 'pdbslot' instead of slot in the same command dialog (and this applies to the Xpedition flow as well).