You can increment date by day with the help of strtotime() php function.
In following example we are increment specified date by 1 day (next day date).
$your_date = strtotime("1 day", strtotime("2017-08-24"));
$new_date = date("Y-m-d", $your_date);
//$new_date will be "2017-08-25"
Here “1 day” is number of days that you wish to increment in a particular date. It should not be less than zero.