One concept of reversal of time is that everything, i.e. radiation, expansion of space, particle etc suddenly stops and begins to move backwards at the same speed. Will it be the movement of time backwards? No, time would still be moving forward only it may appear to be going backwards. But there are things that are not reversible i.e. for instance radiation cannot come out of a black hole ….
We can’t go back in time. No such restriction on moving up in time.