The Windies have already won the Twenty20 International series, but winning the last two games is still crucial for South Africa in the lead-up to the ICC Women's World T20 next month.
The Windies took a 2-0 lead in the five-match series by winning the first two games, and South Africa's hopes of bouncing back were washed away in the rain in the third game.
"It’s very disappointing about the match being rained out the other night," said du Preez, the senior wicket-keeper batter. "We’ve had a lot of chats and had the opportunity to train and the girls are ready to change things around. We know that there’s a lot at stake and we really wanted to play for the win.
"It’s, unfortunately, one of those things in cricket, you can’t change the weather so we need to focus on the controllables. Right now we’re looking to finish the series with winning both remaining games and give ourselves good momentum going into the World T20."
The three-match ICC Women's Championship one-day international series ended 1-1, but South Africa haven't had a good time since the change in format.
Right now we’re looking to finish the series with winning both remaining games and give ourselves good momentum going into the World T20
"It’s definitely not fun losing matches when you know the quality that you pack as a team like we have," du Preez admitted. "It plays on the confidence but the really great thing about this team is how much we really back each other and how we’re always there for each other.
"I think it’s helped being in the West Indies because it’s such a beautiful place to tour and we’ve spent a lot of time together as a team off the field as much as we have on the field and we’ve been able to lean on each other that way. We have this great group of youngsters who have brought a lot of new energy and enjoyment to the team and are reminding us to see the lighter side of life."
Playing against the defending World T20 champions – in the Caribbean, also the venue for the marquee event – had come as a good opportunity for the South Africans to raise their game.
"I think the word for it is ‘frustrated’," du Preez said. "We know that we are better than the performances that we’ve put on. It’s one of the things we’ve been talking about, we don’t seem to be walking our talk.
"For us as a team to be able to move forward, we have to find a way to be more consistent. That is an area of concern that we’ve have for a while, we know we’re better than that. As senior players, myself as well, we need to start putting our hands up and show the little ones how it should be done and lead from the front.
"I think we’ve got what it takes to take them (the Windies) on and that skills-wise it’s just about putting what we talk about into practice. Sometimes I think we over complicate things and over think it.
"At the end of the day, it’s just bat against ball and we just have to go out there and have fun and play for the little girls that started playing this game and the reason why we fell in love with the sport in the first place."