By definition, if there is negative expected value, simply changing your betting strategy won't help. Any short term fluctuations would be from "luck".
The famous MIT black jack team was able to 'take down the casino' by counting cards and waiting for expected value to swing positive, and then placing large bets at that time. If the game is truly random and negative (like all well-constructed casino games should be) then there should never been an opportunity for positive expected value.