congratulations, that is great news! i'm happy for you!
first of all, if you felt like ketamine treatment wasn't as helpful as you wanted it to be in the past, it is a good idea to reflect on why. is there something you'd like to do differently this time?
i haven't done ketamine therapy, but i have taken psychedelics with the intention of improving my mental health. so i can't give specific advice for ketamine therapy, but here is what i do before and after i take psychedelics:
for a day or two before treatment, try to keep a clear mind by decreasing internet use and not taking recreational drugs. personally i like to engage in calming hobbies that let my mind wander, like making art or spending time in nature.
it helps to reflect on what your intentions and hopes are for your upcoming treatment. identify one or two things you'd like to work on during your ketamine session, while also being open to the possibility that your ketamine session might go differently. basically, have an idea of where you want to go, while accepting that ketamine might take you elsewhere--that's the beauty of psychedelics :)
for a day or two after treatment, it helps to reflect on the experience you had in your session. sometimes it's nice to just think about your experience. sometimes it's nice to start a voice recording and ramble. sometimes it's nice to write down what you're thinking/feeling, like a stream of consciousness. sometimes it's nice to answer a few structured questions like: what happened during my experience? how did i feel? what felt meaningful, what was my mind telling me? what did i learn/discover? how would i like for myself or my life to change? any way you want to reflect is good, it doesn't have to be something specific, and it doesn't have to be the same every time, just do whatever feels best.
similar to before your session, try to keep a clear mind by decreasing internet use and not taking recreational drugs. let yourself do whatever your body and mind feel like doing, don't force yourself to do anything specific. for me, sometimes i feel like going on a walk in the forest. other times, i feel like staying indoors and making art. sometimes, i want to meditate. other times, i want to keep my mind and body active. sometimes i want to be alone. other times i want to spend time with others. just do whatever feels right in the moment, and make sure you get enough sleep and food!
in the weeks or months afterwards, i like to focus on 1-2 lessons i learned, and make a couple changes in my life based on these lessons.
i wish you good luck!