Pandas time series optimization problem: add year
Make a pandas Timedelta object then add with the += operator:

x = pandas.Timedelta(days=365)
mydataframe.timestampcolumn += x


So the key is to store your time series as timestamps.  To do that, use the pandas to_datetime function:

mydataframe['timestampcolumn'] = pandas.to_datetime(x['epoch'], unit='s')


assuming you have your timestamps as epoch seconds in the dataframe x.  That's not a requirement of course; see the to_datetime documentation for converting other formats.