Updating dates globally in monthly spreadsheet.

Hi! I use a spreadsheet to keep track of my monthly budget. I have my bills listed in each pay period. When I add a new month or update the dates to the new month, it is very tedious to change one month to the next. I.E.: 6/8/2018 to 7/8/2018. The dates in the pay period fluctuate when the payments need to be sent out, so they can't be done all at once. The month has to be updated manually, even if the day and year stay the same. Is there a way to update the month in the new section without changing the day and year?