One thing that proved effective everywhere is allowing the deviations from the standard language and teachers locally teaching the dialect version - different pronounciation, a bit different vocabulary, different songs perhaps. Ideally locally published books and media filling in the gaps (using local words, etc).
State and internet, however, are still going to be slowly erasing unique identities and merging them.
The thing is that the teachers don't necessarily know the local dialect, they are the wrong generation - too young.
Plus they probably don't come from that area.