1)    One who wants to change his clothes during these days, should wear them beforehand, for an hour, so that they will no longer be “laundered”, and he may thereafter wear them. (Ben Ish Chai Devarim 12)

2)    If he remembers on Shabbos that he had not prepared clothes, he may not prepare on Shabbos for the week. He may, however, remove his clothes in the evening as normal, and put on fresh clothes in the morning, so that they will be ready for the weekday. (ibid). Similarly, if he sleeps in the afternoon of Shabbos, he may put on fresh clothes when he gets up, so that he will have for the weekday after. (Shaalos Uteshuvos Betzeil Hachochmah 4,138)