1. In Autocad, Express tools tab., in the blocks panel, select the export attributes command.
2. When prompted, enter a file name. A text file is created with the first line containing titles.
HANDLE BLOCKNAME TAG1 TAG2……TAG..n
3. In AutoCAD drawing block edit your block and change the Tag name.
4. After saving the block, you need to synchronize your block attributes. On the Insert tab, expand Block Definition panel and select the synchronize command.
5. You will lose all the values in the tags that have been changed.
6. Open the text file created in step 2 above and rename the Tag names to match the revised blocks Tag names. Save the text file after making the change.
7. In the AutoCAD drawing, in the Express tools tab, in the blocks panel, select the import attributes command. Select the text file that you revised in step 6.
As the text output file contained the handles of the blocks, AutoCAD will use this as a key to index the values in the text file to the blocks in the CAD drawing.
If there is an easier method let me know. Ideally there should be a checkbox in the block editor or a prompt when you save the block that will give you the option of holding the values in the changed tag.