If your IKEv1, or even SSL, configuration already exists, the ASA makes the migration process simple. On the command line, enter the migrate command:
migrate {l2l | remote-access {ikev2 | ssl} | overwrite}
Things of note:
Keyword definitions:
l2l - This converts current IKEv1 l2l tunnels to IKEv2.
remote-access - This converts the remote access configuration. You can convert either the IKEv1 or the SSL tunnel groups to IKEv2.
overwrite - If you have a IKEv2 configuration that you wish to overwrite, then this keyword converts the current IKEv1 configuration and removes the superfluous IKEv2 configuration.