To Re-create the Boundary Object for a Hatch Object
Select the hatch object.
On the ribbon, Boundaries panel, click Recreate Boundary.
At the prompt, specify the type of object to create as the new boundary, and whether to associate the boundary with the hatch.
Press Enter, or click Close on the ribbon to apply the hatch and exit the command.
Note:
You can also right-click an unbounded hatch object and choose Generate Boundary; however, this option does not allow you to create an associative boundary.
In some cases, it is easier to delete the hatch object, and create a new hatch object from the desired boundary objects.