[floridarolf]

Auctare is the frequentativum to augere. Like in rising again and again and again...

[Blennos]

I don't think it is from auctare but is rather the past participial form of augeo. Cf passage from Clodius Albinus:

Quae familia hodie quoque, Constantine maxime, nobilissima est et per te aucta et augenda...