In reply to Misha:
Sounds like you've been doing the same kind of routines for a fair while. So the first thing is that it's generally considered best to change one's training after a period of six weeks or so. After that time the body's adaptation response is likely to slow or even stop.
But of course climbing is not just physical. The broad areas are technique, mental and physical. Each one of these can be broken down into further sub sections. So one can improve at all these things too some which will yield better results than others.
If you're going to embark on some non climbing training (eg, weights, fingerboard, core etc.) then you need somewhere to do it. Somewhere where you feel comfortable and happy to go to (or maybe that's even a space at home). I think this is vitally important point if you're to keep up what you're doing. A training partner can also be good though not essential.
In terms of motivation I think that builds as you see yourself get stronger at the exercises you're doing. More reps, heavier weights or progressing to harder exercises that you couldn't do before is great motivation. Maybe getting started and getting into a routine is the hardest part. I don't think you jump into a big training programme. You need to figure out which exercises to do and how to them, one at a time.
In terms of figuring out weaknesses I don't think it's necessarily so hard to do oneself. For instance you probably already have some idea of which styles of climbing you're good at and those you're not. Maybe it's roofs, or pocket climbing or crimping or whatever. Another way is to honestly analyze why you don't get up something. Is it a mental thing, loss of concentration or slight fear holding you back, technique: maybe not using momentum the best way or not finding the best sequence or physical: you simply too pumped to carry on, or those particular moves are hard for you etc. You need to be specific, not just conclude I'm not strong enough. None of us ever are.
For me what seemed to work getting me from 7c to 8a was figuring out a way to improve at fingertip pull ups which I absolutely suck at. I ended up using bigger blocks than normal, and making my own way to attach weights to my wrists and training in a specific way. I also think dong strenuous boulder problems on the Foundry wave for some weeks was pretty helpful - first just getting up a specific problem, then working on doing them 2 or 3 times in succession as I progressed.
I'd also add another vote to Dave Mac's 9 out 10 climbers if you haven't got it.