Automatically copying the formula whenever I INSERT rows IN BETWEEN rows, not at the end of the row

What I want to happen is that whenever someone insert a new row in between rows, the formula would have also copied there instead of dragging the column again and again.

Here's the code that we're using:

=ARRAYFORMULA(IF(D4="","",(sum(IF(D4<300, 0, ROUNDUP(IF(D4<3648, (((D4+100)*0.465)+200), (((D4+100)*0.48)+150))))))))