New columns not being added to already existing tables

I have a few new additions to an existing website created using custom tables.

The issue I'm having is that the new table columns arn't being added to the database.

Metabox:

$meta_boxes[] = array(
    'id'          => 'open_day', 
    'title'           => 'Open Day',
    'post_types'  => array( 'academy' ),
    'autosave'        => false,
    'context'     => 'after_title',
    'priority'        => 'high',
    'storage_type'    => 'custom_table', // Important
    'table'           => "{$db_prefix}academies",  // Your custom table name
    'fields'      => array(
        array(
            'name' => "Set the start and end date!",
            'type' => "heading",
            'columns' => 3,
        ),
        // DATE
        array(
            'name'       => 'Start Date',
            'id'         => "{$prefix}open_day_start_date",
            'type'       => 'date',
            // jQuery date picker options. See here http://api.jqueryui.com/datepicker
            'js_options' => array(
                'appendText'      => '(dd-mm-yyyy)',
                'dateFormat'      => 'dd-mm-yy',
                'changeMonth'     => true,
                'changeYear'      => true,
                'showButtonPanel' => true,
            ),
            'columns' => 4,
        ),
        // DATE
        array(
            'name'       => 'End Date',
            'id'         => "{$prefix}open_day_end_date",
            'type'       => 'date',
            // jQuery date picker options. See here http://api.jqueryui.com/datepicker
            'js_options' => array(
                'appendText'      => '(dd-mm-yyyy)',
                'dateFormat'      => 'dd-mm-yy',
                'changeMonth'     => true,
                'changeYear'      => true,
                'showButtonPanel' => true,
            ),
            'columns' => 5,
        ),
        // CHECKBOX LIST
        array(
            'name'    => 'Apply to:',
            'id'      => "{$prefix}academy_open_day_meridiem",
            'type'    => 'checkbox_list',
            'inline'    => 'true',
            'options' => array(
                'AM' => 'AM',
                'PM' => 'PM',
                'FR' => 'Friday',
            ),
        ),
    ),
);

Custom Table:

MB_Custom_Table_API::create( "{$db_prefix}academies", array(
    "{$prefix}academy_notification_title"     => 'TEXT NOT NULL',
    "{$prefix}academy_notification_text"      => 'TEXT NOT NULL',
    "{$prefix}about_title"                        => 'TEXT NOT NULL',
    "{$prefix}academy_description"                => 'TEXT NOT NULL',
    "{$prefix}academy_facebook"                   => 'TEXT NOT NULL',
    "{$prefix}academy_twitter"                    => 'TEXT NOT NULL',
    "{$prefix}principle_note_title"               => 'TEXT NOT NULL',
    "{$prefix}principle_description"          => 'TEXT NOT NULL',
    "{$prefix}academy_image"                  => 'TEXT NOT NULL',
    "{$prefix}principle_popup_photo"          => 'TEXT NOT NULL',
    "{$prefix}principle_popup_title"          => 'TEXT NOT NULL',
    "{$prefix}principle_popup_description"        => 'TEXT NOT NULL',
    "{$prefix}academy_title"                  => 'TEXT NOT NULL',
    "{$prefix}academy_address_line1"          => 'TEXT NOT NULL',
    "{$prefix}academy_address_line2"          => 'TEXT NOT NULL',
    "{$prefix}academy_address_town"               => 'TEXT NOT NULL',
    "{$prefix}academy_address_county"         => 'TEXT NOT NULL',
    "{$prefix}academy_address_postcode"           => 'TEXT NOT NULL',
    "{$prefix}academy_map"                        => 'TEXT NOT NULL',
    "{$prefix}academy_opening_times_title_note"   => 'TEXT NOT NULL',
    "{$prefix}academy_meridiem"                   => 'TEXT NOT NULL',
    "{$prefix}academy_opening_times"          => 'TEXT NOT NULL',
    "{$prefix}academy_find_us_title_note"     => 'TEXT NOT NULL',
    "{$prefix}academy_find_us_information"        => 'TEXT NOT NULL',
    "{$prefix}academy_contact_title_note"     => 'TEXT NOT NULL',
    "{$prefix}academy_contact_email"          => 'TEXT NOT NULL',
    "{$prefix}academy_contact_phone"          => 'TEXT NOT NULL',
    "{$prefix}meet_the_team_title"                => 'TEXT NOT NULL',
    "{$prefix}meet_the_team_group"                => 'TEXT NOT NULL',
    "{$prefix}noticeboard_group"              => 'TEXT NOT NULL',
    "{$prefix}footer_gallery"                 => 'TEXT NOT NULL',
    "{$prefix}open_day_start_date"                => 'TEXT NOT NULL',
    "{$prefix}open_day_end_date"              => 'TEXT NOT NULL',
    "{$prefix}academy_open_day_meridiem"      => 'TEXT NOT NULL',
    "{$prefix}academy_video_url"              => 'TEXT NOT NULL',
    "{$prefix}academy_video_placeholder"      => 'TEXT NOT NULL',
));