  Many results from astrophysical observations point to a 27% contribution of
non-baryonic dark matter to the mass-energy budget of the universe. Although
still elusive, strongly motivated candidates in form of weakly interacting
massive particles could explain the nature of dark matter, and their
annihilation or decay would give rise to detectable signatures in gamma-rays.
In 2012, the H.E.S.S. collaboration started taking data with the largest
imaging atmospheric Cherenkov telescope in the world which significantly
lowered the energy threshold of the already operational four-telescope system.
In particular, due to its location and improved performance at low energies,
the H.E.S.S. experiment is now in a position to extend the search for dark
matter line signals down to the 100 GeV mass range. The sensitivity to line
searches with a new full likelihood approach will be discussed and preliminary
results from observations with the second phase of H.E.S.S. will be presented.
