How to make number of stages of rectifier to be dynamically reconfigurable

Basically, RFID tag is a passive device. It harvests the energy from RFID reader. So, rectifier is the basic block in the passive tag. Rectifier's dc output voltage is then given to regulator, followed by Modulator, demodulator, POR.

I have designed a rectifier for low power applications for RFID Tag. It has 4 stages. My idea is to bypass the last stage if the voltage at the third stage is enough to drive the next module, regulator.

Since there are 4-stages, I am planning to bypass the last stage as the energy harvested depends on the distance between tag and reader. If tag and reader are near to each other, then we may get higher voltage at the third stage. If we can bypass the last stage, we may save some power.

Now, please suggest me what are the ways/circuit to be added so that I can bypass the last stage so that I can save some power.

In the attached circuit diagram, there are 4-stages of rectifier. Now, my intention is to bypass the last stage based on the output of third stage. How to achieve the same?

Your picture does not show what is in the RF/Vxx blocks. You can leave the voltage handled by the regulator. Bypassing one rectifier stage can be done by a series MOSFET in each rectifier output but it makes the rectifier complex while regulators handle the problem without adding complexity.