Middleware-based database replication protocols are more portable and flexible than kernel-based protocols, but have coarser-grain information about transaction access data, resulting in reduced concurrency and increased aborts. This paper proposes conflict-aware load-balancing techniques to increase the concurrency and reduce the abort rate of middleware-based replication protocols. Experimental evaluation using a prototype of our system running the TPC-C benchmark showed that aborts can be reduced with no penalty in response time.