bimonthly to monthly data

I have bimonthly data for credit card interest rates, but I want to convert that range into monthly data, so what I was thinking of doing is repeating the data for each month that makes up the bimonthly data, but since the column in Excel is long, I don't want to do the task one at a time, adding a new row and pasting the repeated data for the month I am missing from the data into bimonthly, how can I do the task much faster?