Bcm63xx router - need help to increase spi flash (32 mbit -> 128 mbit)

Hello. I have my old router DSL-2640U C4 (main chip bcm6328). I want to make printserver from it. I soldered USB connector and other components, but problem in spi flash size - it too small. I tried to to rewrite full dump from original to new 128 mbit flash, but booting stops in cfe mode (I also tried to increase original dump in hex editor, but nothing happened). Can anybody help me understand, what I need to do ?