Comment by GuB-42

Maybe an effective answer would be to combine DEET with an insecticide.

Mosquitoes attracted to DEET will die because of the insecticide. Usually, for personal protection, we tend to prefer repellents, as we don't want to get bitten, killing the mosquito after the fact is not very useful. But here, the idea is to put some evolutionary pressure against mosquitoes not repelled by DEET.

There are also repellants other than DEET. Icaridin being the best alternative. It is almost as effective as DEET without many of its drawbacks. Some essential oils too, as you said, but I don't think any of them have the effectiveness of icaridin or DEET.