上档次 is a colloquial verb-object phrase meaning 'to reach a certain level of quality/class' or 'to be up to standard.' It's often used for products, services, or events that look or feel high-end. You can use it in constructions like 这顿饭很上档次 ('this meal is quite upscale'). It's a separable phrase: 上了档次 ('has become classy'), 上不了档次 ('can't reach that level').