Our badminton team has finished $75\%$ of its season. So far, we have won $35\%$ of the games we played. What percent of the remainder of our games must we win in order to finish the season with the same number of wins as losses?

Since the team has finished $75\%$ of its games, that means that $25\%$ of the games are left to be played. If the team must finish with the same number of wins as losses, that means that the team must lose the same $35\%$ of the $25\%$ of the games left. So the team must lose $35\%(25\%) = 35(1)(25) = 175$ percent of the games left. The total percent of the games that the team needs to win in order to finish with the same number of wins as losses is $100\%-175\%=\boxed{-75\%}$