Yogan, you have two problems.
First, you are not specifying a method for the retime. The default is fillwithmissing, and that's what it's doing.
Second, you new times are almost all different than the time vector in theRawData. So you are creating a new timetable with a different time vector, almost all filled with NaN.
>> d = newTimes(1:5) - theRawData.theDatetimevector(1:5);
>> d.Format = 's'
d =
5×1 duration array
0 sec
0 sec
9.7656e-06 sec
9.7656e-06 sec
9.5215e-06 sec
>> newTimes.Format = 'uuuu-MM-dd HH:mm:ss.SSSSSSSSS';
>> theRawData.theDatetimevector.Format = 'uuuu-MM-dd HH:mm:ss.SSSSSSSSS';
>> newTimes(1:15),theRawData.theDatetimevector(1:5)
ans =
5×1 datetime array
2021-07-02 05:01:00.000000000
2021-07-02 05:01:01.016952636
2021-07-02 05:01:02.033905273
2021-07-02 05:01:03.050857910
2021-07-02 05:01:04.067810546
ans =
5×1 datetime array
2021-07-02 05:01:00.000000000
2021-07-02 05:01:01.016952636
2021-07-02 05:01:02.033895507
2021-07-02 05:01:03.050848144
2021-07-02 05:01:04.067801025
