Reference: Majmoo’ Fataawa Samaahatu ash-Shaykh Ibn Baaz – Volume 6, Page 96, Fatwa No.45
Question: Is it permissible to change the ihraam [in order] to wash it?
Response: There is no harm in washing the ihraam [clothing] or changing it and using [other than that] a new or washed ihraam [clothing].