父组件代码
<template>
    <div>
        <div>
            <h1>父级</h1>
            <button @click="handleLoad">点击重新加载子级</button>
        </div>
        <children :key="timer"></children>
    </div>
</template>
<script>
import children from '@/components/parent/children'
export default {
    name: 'parent',
    components: { children },
    data () {
        return {
            timer: ''
        }
    },
    methods: {
        handleLoad () {
            this.timer = new Date().getTime()
        }
    }
}
</script>

子组件代码
<template>
    <div>
        子级
    </div>
</template>
<script>
export default {
    name: 'children',
    data () {
        return {}
    },
    created () {
        console.log('重新加载啦')
    }
}
</script>