POKE 52037,0

This removes the code which subtracts one unit from the time.

52036

SUB 1

POKE 42528,0

This simply removes the following command, which would otherwise decrease the players lives.

42528

DEC (HL)

POKE 48985,201

POKE 42457,42

This alters:

48985

RET NZ

To simply return regardless of the flag:

48985

RET

And also changes:

42457

JP NZ,42599

To the following (which is overwritten immediately, so just never actions the jump):

42457

LD HL,42599

POKE 49778,nn

POKE 49779,nn

For example, to set 2000 seconds:

POKE 49778,0

POKE 49779,32

Or, to set 750 seconds:

POKE 49778,80

POKE 49779,7