If someone you haven't seen in a while asks to meet up at the last minute, it's easy to make an excuse that you already have plans. And, since no one would know that you just couldn't mustering the energy to leave the house, it's unlikely that there'd be any hard feelings if it doesn't work out. But, if you'd go, then it's likely that this person is at least a good "medium friend".
Overcoming the inertia of relaxing at home is hard, especially when you're in your pajamas. So, if you're considering whether it's worth investing more time into a relationship, think about whether you'd be willing to leave the house for that person. If you're not, then deepening your relationship doesn't need to be a priority. You're better off saving your energy to spend time with other friends.