How to perform a chain genesis parameter update ?

[dev573]

Hi team, I have been running a cosmos based network, and now i want to make some changes in genesis file. But I don't want to lose my data as well. Let's say if my current block is 999 and i made some changes in genesis file, after making change on that genesis file. My chain should run from 999.
can i get any reference for the same or any help on this.

Thank you