Simulated Annealing for a protein-ligand

Dear all,
I performed a 300-ns MD simulation for a system of protein-ligand, now I want to increase the temperature (from 300 to 330) using “single simulated annealing”, and continue my MD for a 100 ns.
The problem is that as I want to continue my MD, I should update my .tpr file to a new one. But, I don’t know how to add the simulated annealing parameters into the .tpr file. Basically, we need to add these parameters in the md.mdp file, but I don’t want to start an MD. I want to continue my previous MD.
Does anybody know how to deal with this issue?
Thank you