And one more idea.  An example
Federer win
yes @2
no @2
I have 1BTC - is all what i have on my balance
next i make a bet  YES - 1BTC (all-in, my balance now is a zero)
Federer play nice and after a some time , i see that No is a @4
and i make a bet  No - 0.5BTC (in same time when i have zero on my balanse)
And what we have
Yes - profit +0.5BTC
No - profit +0.5BTC
I can't lose more than 1BTC but i make bet in a summ at 1.5BTC, at time when i have only 1BTC in my balance
if lose Yes - 1 and + 2-0.5 at No
if lose No  - 0.5  and + 2-1 at Yes

I hope you understand me)
with this step you can up  liquidity on your markets

also is work to another way
Let's say Federer play as sh*** and i want fix my losses and save some money
now odds to No @1.3
i make a bet  No - 1.54 BTC
Yes - lose -0.54BTC
No - lose -0.54BTC
I'm a save 0.46BTC . Still can't lose more than 1BTC but i make bet in a summ at 2.54BTC, at time when i have only 1BTC in my balance

So the more bets - the more fees
Also with this system, players can make much more bets. Because they will be have much more free money for another markets