This will shift everything from A2 to the right by 1 column, leaving A2 empty and ready to insert the new data.
Do be aware that this will also copy across the formatting of A2.
So make sure any borders etc. are placed on A1 and not A2.
function addNewCell() {
var ss = SpreadsheetApp.getActiveSpreadsheet();
ss.getRange("A2").insertCells(SpreadsheetApp.Dimension.COLUMNS);
}
And if you wish to shift A2 across multiple cells, use a range
ss.getRange("A2:C2").insertCells(SpreadsheetApp.Dimension.COLUMNS);
Obviously this particular code will move them 3 across