Note: my comment above assumes you are wearing soft contact lenses. If you are wearing rigid contact lenses, then yes, you can thoroughly clean and soak the lens and wear it. Instead of falling back on old contact lenses it would be better if you had a working pair of glasses for those times when your current contacts are "being serviced" (by which I assume you mean, being polished).
Under no circumstances should you wear a lens that has gotten dried out. It sounds like you are very abusive in your contact wearing habits. You are inviting a disastrous eye infection called a corneal ulcer, which can lead to permanent blindness.