  The standard model of Gamma-Ray Bursts afterglows is based on synchrotron
radiation from a blast wave produced when the relativistic ejecta encounters
the surrounding medium. We reanalyze the refreshed shock scenario, in which
slower material catches up with the decelerating ejecta and reenergizes it.
This energization can be done either continuously or in discrete episodes. We
show that such scenario has two important implications. First there is an
additional component coming from the reverse shock that goes into the
energizing ejecta. This persists for as long as the re-energization itself,
which could extend for up to days or longer. We find that during this time the
overall spectral peak is found at the characteristic frequency of the reverse
shock. Second, if the injection is continuous, the dynamics will be different
from that in constant energy evolution, and will cause a slower decline of the
observed fluxes. A simple test of the continuously refreshed scenario is that
it predicts a spectral maximum in the far IR or mm range after a few days.
