i have used the watcha exraction method
STB
now i have lye with mimosa from the previous extraction
can i add just new mimosa to the extraction ?

You could, but it's definitely not the best way to go about it and I have no idea what sort of problems it will cause. You'd most likely be better off just doing a whole new extraction. Personally, I don't believe there is any room to cut corners when it comes to DMT or extracting it from plant sources.