Simple, if 50+1% (you could go further a require a "super majority of 60%") of the registered voters in a given riding wanted their MP recalled there would be another by-election.
Clearly in ridings where the the MP was elected with over 50% of the vote this would hardly ever be an issue, but in a riding where the MP was elected with ~40% of the vote, said MP would have to insure they appeal to at least 50% of voters, including voters that didn't vote for him/her, resulting in more cooperation by parties, and more importantly, MPs having to defer to the wishes of their riding as opposed to a party as a whole..........i.e they would be representing their constituents versus the party apparatchik, like they are suppose to.