Changing ssh keys on a Ubuntu Azure VM from the Dashboard

I have an Ubuntu VM running on azure. I need to ssh connect to it but I have lost my private key since my home partition has gone. So, I reinstalled the OS on my local machine and regenerated a new pair pf private/public keys -- which I am already using for github, bitbucket, ecc. Is there any way to set my new public key on the Ubuntu VM from the Azure Portal?