We recommend to take a snapshot of the EBS before you upgrade a kernel to be safe, in case something goes wrong you can bring up another EBS from that snapshot.
Upgrading a kernel version depends again on the kind of OS you are running.
In case of Amazon Linux to check the current kernel version
$ uname -sr –> gives the current kernel version
$ sudo yum check-update kernel –> lists the latest stable kernel update
$ sudo yum update kernel –> should update your kernel to the latest version.
Restart your EC2 after the update and check the version
$ uname -sr
For any other distributions let us know the one you intend to update and we will tell you accordingly.