Paradise has another ear infection,

she had one about 6 months ago in her left ear, now she has one in her right ear. The vet flushed out her ear, gave her a shot and and sent us home with a cleaner and onitment to use on her ear twice a day for the next 2 weeks and the recommended cleaning her ears daily. We had been cleaning them weekly.
He thinks its a yeast infection, she is currently on Royal Canin. Does anyone have any suggestions on what to use so they don't keep re-occuring? He said she is no way in need of a operation to open up her ears.
She was so misable over the weekend. My poor little girl.
thanks,
Michele