To truly preserve everything that was "you" at any particular moment, you would need to preserve all of the synapses in your brain. This is not undoable but it is not particularly palatable and would not be reversible biologically without reconstructing you in silico or a clone...the later also unlikely and possibly needlessly intensive for the purpose. Researchers have been able to do this for decades in animal, but it requires vascular perfusion with paraformaldehyde and glutaradehyde while the heart is still beating to ensure all the microscopic nooks and crannies are pickled within seconds. Essentially you would have to kill your biological form to accomplish this. I personally don't have any issue that any faithful reconstruction of such wouldn't still be "you", at least not any less you than those natural forces which effectively make an imperfect clone of you from day to day with the passage of time do right now. The real question is for what purpose? I think we need to honestly ask ourselves what really is identity, and I think it's a lot less meaningful or more meaningful depending how you think. We probably share so much in common with other human beings that parts of our identity...and probably the most important parts...are already transcribed into the future through our children, language, ideas, etc, and that even in one lifetime our identity changes so radically that there are probably people out there who are a more faithful representation of the person you were 20 years ago than the one you are today...Ship of Theseus and all that. There may be some niche uses for such technologies, but I think in general they will be superseded by alternate ways of viewing our identity and even better ways to cement a positive influence into the future. Probably our best shot at immortality may simply to be a good person.