I think it depends on how bad your bone healing is. if it's really bad like a non-union, I would think additional surgery like a bone graft is the only solution. a bone graft is a surgery to replace the missing bone, usually taken from the hip.
if your healing is just slow, then I think more time will be enough but some things I've read about that might help are taking more supplements, the exogen machine, additional weight bearing (be careful though), stem cell injections, bisphosphonate drugs. I'd ask a doctor though who would be more qualified to speak to these options
