aha ok i did it once.. try to see when how many rows you need that it comes to the end of page. lets say 25 rows will come to end. and you have here in your picture 4 rows so you ll add 21 inital row to the your internal table.
describe table itab lines lv_lines.
if lv_lines lt 25.
lv_add = 25 - lv_lines.
do lv_add times.
append initial line to itab.
enddo.