  While the recent discovery of a Higgs-like boson at the LHC is an extremely
important and encouraging step towards the discovery of the {\it complete}
standard model(SM), the current information on this state does not rule out
possibility of beyond standard model (BSM) physics. In fact the current data
can still accommodate reasonable values of the branching fractions of the Higgs
into a channel with `invisible' decay products, such a channel being also well
motivated theoretically. In this study we revisit the possibility of detecting
the Higgs in this invisible channel for both choices of the LHC energies, 8 and
14 TeV, for two production channels; vector boson fusion(VBF) and associated
production($ZH$). In the latter case we consider decays of the $Z$ boson into a
pair of leptons as well as a $b \bar b$ pair. For the VBF channel the
sensitivity is found to be more than $5 \sigma$ at both the energies up to an
invisible branching ratio ${\cal B}r_{invis} \sim 0.80$, with luminosities
$\sim 20/30 {\rm fb}^{-1}$. The sensitivity is further extended to values of
${\cal B}r_{invis} \sim 0.25$ for $300 {\rm fb}^{-1}$ at 14 TeV. However the
reach is found to be more modest for the $ZH$ mode with leptonic final state;
with about $3.5 \sigma$ for the planned luminosity at 8 TeV, reaching $8
\sigma$ only for 14 TeV for $50 {\rm fb}^{-1}$. In spite of the much larger
branching ratio of the $Z$ into a $b \bar b$ channel compared to the dilepton
case, the former channel, can provide useful reach upto ${\cal B}r_{invis}
\gsim 0.75$, only for the higher luminosity ($300{\rm fb}^{-1}$) option using
jet-substructure and jet clustering methods for $b$-jet identification.
