A method for reprogramming data, performed by a processing unit, is disclosed to include at least the following steps. After a page of data has failed to be programmed into a first block of a storage unit, it is determined whether the failed page is an upper page or a first lower page. When the failed page is an upper page, a host page number associated with a second lower page of a wordline including at least the failed page is obtained, a second block is selected, and an access interface is directed to reprogram data from the second lower page to the upper page into the second block.