You should be able to void the original e-signature envelope.  Once voided, you can change the email in the Client Information section and then go back to the e-signature section and Start A Request.  Double check that it is not using another envelope, but I had to do something similar this year, and it seemed to work without costing more. 

The key is to void the original first.  Don't re-submit because that will just send the original with the same email as before.