Recovery

Hello Victory. I think there are many types of recovery and as everyone is pointing out huge variations in how much and how long improvement continues. This article on neuroplasticity (which never stops) is interesting and maybe one of the reasons why people with incomplete injuries can continue to gain function long after the "2 year window" which doctors sometimes use as the cut off point for recovery.
www.spinalcordinjury-paralysis.org/forums/viewtopic/11775/54901
I guess complete injuries are different and have no experience of these. 
Peter is a bit of an oddbod in that his injury stems from an op (laminectomy C4-C7) that didn't go to plan and left him with little mobility. He has weakness in all 4 limbs and spasticity in his lower limbs. His hands are affected too. He is now over 5 years post and is still improving and gaining function. He can now do a (very simple) routine at the gym - 7 mins on treadmill, 5 mins on cross trainer and some upper body weights which even 6 months ago seemed impossible. Not huge but he is increasing his times every couple of weeks. He is doing stamina walks at home every day and is improving his time and distance slowly but positively. 
We think his improvement is mainly down to finding ways to control his spasticity and tightness which has impaired his movement. In the early days if he went even a little over what his muscles could manage he would tighten up like an elastic band and have to be "detangled" by the physiotherapist. He still gets very tight in his legs if he pushed too much but not the dramatic reaction of the early days. So he just keeps chipping away at it - 2 steps forward and one back mainly. He uses meds to control tightness and nerve pain  and we keep lowering these as he finds more ways to get his muscles working. 
He has  used tools like the alterG antigravity walking machine which although used by athletes recovering from injury is also great for impaired mobility. Hydro is also very helpful.
He has weekly physiotherapy from a very dedicated and talented neuro physiotherapist and has been taught some Feldenkrais exercises which are teaching him new ways of movement (in the same way that a baby learns to walk). These are all very small movements so great for "bad" days.
It is a way of life and not as demanding as I am making it sound - but it is working and way past the 2 years of recovery he was told he would have. We are not expecting him to recover all the movement he had pre op (partly as he is late 60s) but he is finding new ways to do things, chipping away at his muscle tightness and going forward. Who knows how much more function he can gain.
So short answer to your question is - yes, gaining function after 5 years plus is possible if you have an incomplete injury.
Good luck - hope you find your way to the recovery routine/programme that works for you.