Refresh the data displayed within an ALV object grid

 CALL METHOD gd_tree->set_table_for_first_display
    EXPORTING
      is_layout       = gd_layout
    CHANGING
      it_fieldcatalog = gd_fieldcat
      it_sort         = it_sortcat
      it_outtab       = it_report.
 CALL method gd_tree->REFRESH_TABLE_DISPLAY.
 CALL METHOD cl_gui_cfw=>flush.