warm sth up

to heat food that has already been cooked

重新加热(食品)

You can just warm up the leftovers from yesterday's meal in the microwave.

你或许只需用微波炉热一热昨天剩的饭菜就可以了。

OK, I was going to cook dinner first, but I don't think I have enough time now. I'll just warm up some leftovers in the microwave.

好的，我正准备先做晚饭呢，但是我觉得时间不够啦，那我就在微波炉里热一点剩饭吧。