What should i do with my bettas medication?

i put it in yesterday in a 2.5 gallon tank along with my female betta which had body slime fungus.so in the morning i saw that she was all better now and she had nothing in her body left.so should i remove the medicine and put new water in or should i still leave the medicine in there because the box says that it takes more than 48 hours for the whole medicine to work but she seems all better already.