Before asking for a new activation code to be sent, please check your Junk/Spam folder for the email.
If you haven't received your activation code and you still have the registration window open, on the page where you Enter the activation code there is a button called Edit email/Re-send code. Select this button and you'll be able to change your email address and/or request a new activation code to be sent.
If you haven't received your activation email and you've closed the register window, you need to restart the Jupiter Investor My Account registration process.