Try this magic spell:
vm.$forceUpdate();
//or in file components
this.$forceUpdate();
No need to create any hanging vars 🙂
Update: I found this solution when I only started working with VueJS. However further exploration proved this approach as a crutch. As far as I recall, in a while I got rid of it simply putting all the properties that failed to refresh automatically (mostly nested ones) into computed properties.
More info here: https://vuejs.org/v2/guide/computed.html