Maybe something like this:
S = load('timetable.mat');
T2 = S.T2;
dt = 1;
t = seconds(T2.Time);
N = round((t(end)-t(1))/dt)+1;
ti = linspace(t(1),t(end),N).';
Vari = zeros(N,1);
for ii = 1:numel(t)-1
Vari(ti>t(ii) & ti<=t(ii+1)) = T2.Var(ii+logical(T2.Var(ii+1)));
end
% Another way to write that loop; may be easier to understand:
%
% for ii = 1:numel(t)-1
%
% idx = ti>t(ii) & ti<=t(ii+1);
%
% if T2.Var(ii+1) == 0 % transition ends with 0
% % (i.e., 0->0, 1->0, 2->0)
%
% Vari(idx) = T2.Var(ii); % use previous
%
% else % transition ends with 1 or 2
% % (i.e., 0->1, 0->2, 1->1, 1->2, 2->1, 2->2)
%
% Vari(idx) = T2.Var(ii+1); % use next
%
% end
%
% end
T2_retimed = timetable(seconds(ti),Vari, ...
'VariableNames',T2.Properties.VariableNames);
figure
plot(T2.Time,T2.Var,T2_retimed.Time,T2_retimed.Var)
legend({'Original','Retimed'},'Location','NorthWest')
