if (!win) then
  lossCount += 1
else
  if lossCount >= 5 then
    lossStartMult = 4

    startCount = numbets -- save starting point   

  end
  lossCount = 0
end

if numbets >= startCount + 100 then
  -- it has been 100 bets since we changed stuff
  -- reset all the values here
end

  if arrayCounter > #myBetArray then
    -- reached end of list, stop betting
    stop()
  end

...
myBetArray = {1,2,3,4,5,6,7,8,9,10}
arrayCounter = 1 -- LUA convention is that array index starts at 1 ;)

function dobet()
...
  if win then
    if arrayCounter < 5 then
      arrayCounter = arrayCounter - 1 -- jump back 1 in the list
    elseif arrayCounter < 10 then
      arrayCounter = arrayCounter - 2 -- jump back 2 in the list
    else
      arrayCounter = arrayCounter + 1
    end
    ... other win stuff ...
  else
    --loss, go to next bet in list
    arrayCounter = arrayCounter + 1
    ... other loss stuff ...
  end
  
  -- check to make sure we don't exceed the array size
  if arrayCounter > #myBetArray then
    -- reached end of list, prevent out of bound error
    arrayCounter = myBetArray[#myBetArray]
  end

  nextbet = myBetArray[arrayCounter]

end

  if myBetArray[arrayCounter] < 5 then
    arrayCounter = arrayCounter - 1
  elseif myBetArray[arrayCounter] < 10 then
    arrayCounter = arrayCounter - 2
  else

--CODE HAS NOT BEEN TESTED!!

... other vars...

biggest = 0
lowest = 100

numBets = 0

function doBet()

  ... stuff ...

  if lastBet.roll < lowest then
    lowest = lastBet.roll
  end
  if lastBet.roll > biggest then
    biggest = lastBet.roll
  end
  
  ... other stuff ...
  
  numBets = numBets + 1
  if numBets >= 1000 then
    print("BIGGEST roll: " .. biggest)
    print("smallest roll: " .. smallest)
    stop()
  end
end

--CODE HAS NOT BEEN TESTED!

if (!win) then
  lossCount += 1
else
  if lossCount >= 5 then
    lossStartMult = 4

    -- NEW COUNTER
    lossStartMultCounter = 0
  end
  lossCount = 0
end

--Increment every roll
lossStartMultCounter += 1

-- if it gets to big, reset lossStartMult and reset the counter as well
if lossStartMultCounter >= xNumberOfBets then
  lossStartMult = initialLossStartMultValue (or whatever else you feel like)
  lossStartMultCounter = 0
end if