  We conduct three-dimensional hydrodynamical simulations of weak jets that we
launch into a core collapse supernovae (CCSNe) ejecta half an hour after the
explosion and find that the interaction of the fast jets with the CCSN ejecta
creates high pressure zones that induce a backflow that results in mass
accretion onto the newly born neutron star. In cases of weak jets, a total
power of 10^45-10^46 erg, the backflow mass accretion might power up to an
order of magnitude more energetic jets. In total, the jets of the two
post-explosion jet-launching episodes have enough energy to influence the
morphology of the very inner ejecta, a mass of 0.1 M_O. Our results imply that
in some, probably a minority of, CCSN remnants the very inner regions might
display a bipolar structure that results from post-explosion weak jets. The
regions outside this part might display the morphology of jittering jets.
