GentlemanJonYou might want to address games that are likely to be very one sided and therefore likely to attract fewer bets by offering a score based bet, such as Froyotech to win by 3 rounds or more rather than just Froyotech to win. The downside is that this isn't automatic and is a bit more difficult to understand for the punter.
One thing to consider with bets being moved or retracted as suggested above is that people will (if they're thinking) place bets on one team on the strength of bets on the other team as much as who they think will win, so bets being retracted will potentially cause an undesirable knock on effect of lots of bets being removed/moved.
It leaves the system open to collusion, two players could make bets, one small and the other very big, and other punters would pile on the other side at the sight of all the loot available. Just before the match or bet retraction time limit the big gambler of the colluding pair retracts their bet. This leaves all the punters on the other side standing to gain much less while the small bettor stands to win a huge amount at very little risk. Obviously there will be more players involved than just a handful, but the potential effect is there.
That's why I was worried about retracting bets, still not sure about moving. Score based bets sounds like a good idea! No one would be crazy enough to bet against Epsilon