Generally this will require a new will or a codicil, i would suggest speaking to a local attorney handling wills to discuss which manner would be most appropriate in your given situation. This should include an examination of all assets and discussion of all changes needed to be made to the will.
Your attoney probably drafted it to include afterborn children. Also. a name change doesn't change who that person is.
If you don't feel that this is okay, then you need to have an attorney draft a codicil which is an amendment to a will.