You can set up your base Stake and Multiplier. After every winning bet the stake will be set back to the base. After a loss it will be timed by multiplier.
For example, if Stake = 1 and Multiplier = 2.5 Bet #1. Stake = 1 - LOSS Bet #2. Stake = 1 x 2.5 = 2.5 - LOSS Bet #3. Stake = 2.5 x 2.5 = 6.25 - WIN Bet #4. Stake = 1 - WIN
You can also use Multiplier Limit to set upper limit after which the multiplier will not increase.