To do this, first click the Manage Invitation button to the right of the invitation on your dashboard. Then, on the next screen, click on the Add More Guests button.
Here, you will be able to enter your guests' email addresses or phone numbers and then proceed to the Send page to send the invite out. You can read more on the different ways to add guests .
Note: This will send the invitation just the newly added guests. It won't resend to guests who have already been sent the invitation.