  We introduce a new method to achieve long lived Bloch oscillations and
dynamical localization of matter wave gap solitons in optical lattices. The
method is based on time dependent modulations of the nonlinearity which can be
experimentally implemented by means of the Feshbach resonance technique. In
particular, we show that the width of the wave packet is preserved if time
modulations of the nonlinearity are taken proportional to the curvature of the
linear band spectrum which for most typical experimental settings are well
approximated by harmonic time modulations of proper frequencies.
