To regenerate the table maintenance generator after adding or deleting a field from table structure, go to Table Maintenance Dialog Generator (SE56).
Enter the Table/View name for which you want to regenerate the TMG and click on Create/Change.
Click on change icon.
Select the appropriate checkbox or all checkboxes and press continue. This is will re-generate the TMG with success message in the status bar.
Click on “Expert Mode” to see more options .
A small correction here . the Tcode is se54