Will blue tits return to same nest box and use net from last year?

Hoping someone can help us...

We have a pair of blue tits keep spending time in a nest box, which other / same? blue tits successfully nested in last year.

I've forgotten to take old nest out from last year, wondering whether its too late to remove / if birds which are spending a lot of time in then, will use it?

What to do? 

Many thanks