The commands you posted above are not enough to change to a newer release of the distro.
The recommended command to move to a new release is:
sudo do-release-upgrade
This should start the process of downloading and installing the new release version, however it will only move to a stable release. If the release you want to move to is still classed as in the development stage, you'll need to append the -d option.
If you want to check which version is currently installed on your system use:
lsb_release -a
This will produce a 5 line output, detailing which exact version of Ubuntu you're using, don't panic when the output starts with the line 'No LSB modules are available', that's perfectly normal.
So your best move is to use the lsb command first to check what version you're on, then if it still says 14.04, issue the do-release-upgrade command. Hope that helps!