Q. Someone asked me if a garment that has tzitzis ripped, how is it to be repaired? The tzitzis themselves are okay, it is just the garment.

A. If the garment ripped in a way that it would disqualify it, as when it does not meet anymore the minimal requirements of garment size, you would have to remove all the tzitzis, then fix the garment and replace the tzitzis (Shulchan Aruch O.H. 15: 3 and Mishna Berura ibid. 8). For smaller tears you can fix it as is.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a