These codes give 4 lives:

Level 2: BVVFKQ4X
Level 3: BXF74YCY
Level 4: BXNVKB3G
Level 5: CMJNFTTM
Level 6: CS4LYC3F

These codes give 5 lives:

Level 7: DBTZQBYC
Level 8: DRDZ49WY
Level 9: FD7CBBHT
Level 10: FD7C76XF