Script to insert new row and copy down formulas that auto increase according to row index?

Instead of getFormulas and setFormulas, use copyTo method:

range.copyTo(newRange); 

This will have the same effect as if you selected the last row and copied it below. In particular, it will also copy down any values that were entered directly into cells. If you prefer such values to not be copied, use getFormulas/setFormulas combination on newRange:

range.copyTo(newRange); newRange.setFormulas(newRange.getFormulas()); 

The effect of the last line: no change of formulas, but the cells that didn't contain a formula will become empty.

R1C1 approach

You can also try replacing the last three rows of addRow with

var formulas = range.getFormulasR1C1(); var newRange = sh.getRange(lRow+1,1,1,lCol); newRange.setFormulasR1C1(formulas); 

This will make sure the references in formulas are remapped as if you copy-pasted them. However, this has a major limitation: setFormulasR1C1 doesn't work correctly with empty string as its argument, which will result in #ERROR! messages in the cells that should be left blank.

The reason R1C1 works differently is that getFormulasR1C1 retrieves formulas in a relative form: for example, a reference from A3 to D2 becomes R[-1]C[3], meaning "one row up, three columns to the right". When the formula is set to, for example, E4 with setFormulasR1C1, the cell reference will appear as H3.

I am currently solve same problem. This post extends previous reply from user79865:

You should use getFormulasR1C1() and setFormulasR1C1 function instead of getFormulas, because they are use relative links to another cells.

Function copyFormatAndFormulas

I write this simple function to copy formats & formulas between ranges:

function copyFormatAndFormulas(rangeSource, rangeDestination) { rangeSource.copyTo(rangeDestination, {formatOnly: true}); var formulas = rangeSource.getFormulasR1C1(); for(var x in formulas) { for(var y in formulas[x]) { if(formulas[x][y] == "") continue; rangeDestination.getCell(parseInt(x) + 1, parseInt(y) + 1).setFormulaR1C1(formulas[x][y]); } } } 

Example:

I modified your function addRow() from your ask:

function addRow() { var sh = ss.getActiveSheet(), lRow = sh.getLastRow(); var lCol = sh.getLastColumn(), range = sh.getRange(lRow,1,1,lCol); sh.insertRowsAfter(lRow,1); var newRange = sh.getRange(lRow+1,1,1,lCol); copyFormatAndFormulas(range, newRange); }