It's not uncommon for us to need to update our block definitions from time to time. You probably follow the same procedure we've all followed for years: Insert the block on the "0" layer... explode it... make the necessary changes... go back into the block command, redefine it... make sure you use the same insertion point or all of the previously inserted blocks will move, and so on. Redefining an existing block is not a very exciting task, tedious at best.
Enter the REFEDIT command to save the day. This awesome command came to us in AutoCAD® 2000 with the chief goal of permitting the editing of attached external references. As it turns out, it's a fantastic block editor as well. Most of us didn't think to try it out on blocks, even though technically blocks are referred to as references as well. To follow along you need a previously inserted block that you're willing to make some minor modification to.
From the Modify pull-down menu select In-place Xref and Block Edit. Interestingly enough, few of us have ever thought to use REFEDIT on blocks, and yet it's mentioned right there in the Modify pull-down menu... but then who has time to sit around and read those menus anyway? Select the block you wish to edit and then you will see the dialog box found in Figure 1.
If the displayed block is correct, click okay to exit the dialog box. You will be asked to select the individual components of the block again for editing—simply put a window around the intended block and press an extra enter. Now you will find yourself in an interesting situation. Everything in the drawing will be grayed out except for the block you're working on. This makes it easy to see what you're working with and keeps everything else out of the way. You will also find that the block has been temporarily exploded and sent back to its original layer for your use.
You will see the REFEDIT toolbar as shown in Figure 2. Even if you're a toolbar hater (I know you're out there) do not get overly ambitious and close this toolbar. We're going to need it to complete this command and I'm sure you don't want to end up in REFEDIT limbo. Make the appropriate modifications and/or additions to the block and then select the last tool in the toolbar with the tooltip "Save back changes to reference" as seen in Figure 3.
If you happen to make a mistake and want to cancel out of the entire operation, on the toolbar select the "Discard changes to Reference" button.
After modifying the block, you will get a nice friendly warning dialog box informing you you're about to redefine your block. Click OK to complete the procedure, and Presto! Your block has been redefined and all of the existing blocks have been updated to reflect the changes you made. No need to worry about the insertion point, REFEDIT will pick the same insertion point for you automatically. It just doesn't get much easier then that.
Give it a try—you'll never go back to the old method ever again!