For example, let's say I'm wearing fresh clothes and then I perform wudu and offer salah. After I complete my salah, I change my clothes and put on trousers that have traces of dry urine on it. So, when the time of next salah comes, I put the fresh clothes back on before praying salah.
But do I have to perform wudu again? Because if I remember correctly, dry urine (or any dry najasah) does not break your wudu.