In your HubSpot account, navigate to Marketing > Email.
On the left panel, click the Sent folder.
Click the name of the email you want to send to more contacts.
Click the Actions dropdown menu and select Send to more.
Hover over the name of the lists or individual contacts and click Include to add them as recipients. You can also select individual contacts or lists to exclude from the send by clicking Exclude.
Please note: if you added any exclusion lists in the original email, they will not be considered when resending the email, so if you want to exclude sending to the same lists, you'll need to reselect them. Any individually selected contacts who you excluded when you previously sent the email will be excluded automatically.