Can't you just have?
targetscore=25000
If score > targetscore
Lives= lives +1
targetscore=targetscore + 25000
endif
targetscore=25000
If score > targetscore
Lives= lives +1
targetscore=targetscore + 25000
endif
No that's far too simple! As a British citizen I won't stand for such a solution! It must be at least 500 times more complicated and involve charging the tax payer in some way.
/sarcasm
Actually that's a very nice solution.