You are always referring to the next element while printing. Just swap the print line with the increment line like this
print("Lotto number",index,"is",lotto[index],"!")
index = index + 1
When you print something like this, you can use format
function, like this
print("Lotto number {} is {} !".format(index, lotto[index]))
Apart from that, you can use a for loop and range
function, like this
for index in range(7):
lotto[index] = random.randrange(1, 9)
print("Lotto number", index, "is", lotto[index], "!")
range
function will give the values from 0 to 6, one at a time, on each iteration.
Even better, you can create a new list using list comprehension, like this
lotto = [random.randrange(1, 9) for index in range(7)]