@Tammy Tang Are you the sender of the envelope? If so go to the Agreements > Sent folder and if the envelope is still in progress then the “Resend” option should be available.
Typically if you go to the Inbox you are just a Recipient on the envelope or receiving a copy of the envelope and would not have the ability to resend the envelope since you are not the Sender o the envelope.
If you had shared access to the envelopes of the Sender with the appropriate shared permissions then you might also have the ability to “resend” from that shared access user’s account.