How to reset the plugins without deactivate the plugin

You could make another function with will (re)set the default option values:

function wpse_91307_set_option_defaults() {
  $options = array(
    'ptechsolcopy_notice'   => 'Copyright ©',
    'ptechsolcopy_reserved' => 'All Rights Reserved'
  );

  foreach ( $options as $option => $default_value ) {
    if ( ! get_option( $option ) ) {
        add_option( $option, $default_value );
    } else {
        update_option( $option, $default_value );
    }
  }
}

Then you could change your set_copyright_options() function into this:

function set_copyright_options() {
  delete_option( 'ptechsolcopy_notice' );
  delete_option( 'ptechsolcopy_reserved' );

  wpse_91307_set_option_defaults( );
}

When you hit the reset button, the only thing you have to do is execute the wpse_91307_set_option_defaults() function.