Traffic shaping, alone, is generally not a cure for packet loss. In fact, it may increase packet loss.
Packet loss might be mitigated by increasing egress buffers (although that may create additional latency and/or have other negative effects) and/or "smarter" drop management (which doesn't help for all traffic types).
More generally, there are QoS techniques, used properly, that may mitigate packet loss or at least mitigate packet loss for more important traffic, but sometimes you need more bandwidth.
In your case, insufficient information to suggest what might help.
