IF USING YOUR HANDS:
may i suggest creating one column with date+time,
if will be easy to increment (write two first lines, select them, then
right clic the small square in the right-bottom, go down, stop on the
final date, in the menu choose to increment as a serial list; not
integer one !)

then put in two adjacent colmuns the formulas:
(example : my column in A, date in B, time in C)
in B1: =DATE(YEAR(A29);MONTH(A29);DAY(A29))
in B2: =TIME(A1)

for each one right-double-clic the right-bottom-square
the formula will propagate down to the end of list

select thoose 2 columns copy / paste-special the values
delete the column A

you have your result

IF USING A MACRO:
then you may add a constant value one to the other
(the step constant must be:
[ {(sec)/60 + min}/60 + hour ]/24 + day
)

and that's all