Is it permissible to delay making up the missed days of Ramadan until after the next Ramadan, given that the day is long and the Maghrib prayer is at approximately nine in the evening, and is it true that it is not permissible to fast during the second half of Sha‘ban to prepare the body for Ramadan?

It is obligatory to make up the days before the advent of Ramadan (definition), and the length of the day is not considered an excuse. Delaying the make-up fast without a valid excuse until the advent of the following Ramadan is a sin and necessitates expiation (feeding a needy person for each day) along with making up the fast, according to the majority of scholars. Fasting after the middle of Sha'ban for someone who has make-up fasts due does not fall under the prohibition.