I'm thinking of selling and replacing my partner's gift
Why would you want to replace their gifts?
Yes, I want to un burden her. She's not always appreciated the thoughtful gifts I give her
If your partner asked for you to replace the gift then it is nice that you are doing so. If the burden is creating stress for your partner, then maybe returning the gift is a good idea to make you both happier.
It's too late to tell her this. I don't feel like she deserves any gifts in the first place.
You should still give her her gifts. It is expected that you would replace the gifts since she had asked for that to happen.