The 3.3km addition is to the roadside Hostal Asturias.
From Jarilla you do not need to retrace your steps. Follow the N-630 and you will rejoin the camino.
Leaving Hostel Asturias there is a much more pleasant, alternative route to Aldeanueva which avoids the main road. It is marked with royal blue arrows. Turn left out of the hostel and follow the road for <1km where there is a blue arrow pointing to the right onto a country path (it’s visible on google maps). The path continues fairly straight, past a factory ??sewage works (also visible on google maps) and eventually joins the main route just after the switchback/dog leg. Word of caution - after a few showers of rain there were some big puddles and the minor streams had become a little difficult to cross, so probably best avoided if there has been any serious rain.