First, I'm gonna call Silver out as full of it on this one: don't you dare lose that pet!!
Second, I'm going to mock your pet:
You call that unbalanced !!!, You're only 197 levels short of being able to codestone train, why you're a disgrace to those of us who are *real* lab rats to complain about such a paltry disparity.
Okay, now I'm going to actually attempt to be helpful, as this is a topic I'm very familiar with, my lab pet has been 300 levels or more behind for the past year, AND I also started over with a second pet, so I know how this works.
Your best option is likely "none of the above", and I'll explain in a moment, but first I want to point out that what you decide to do depends on your goals. If you want to save NP for other purposes and only dabble in the BD, just labbing without really training is fine. If you want to get to the 700 Str Boost, but you don't care about defense negg training may actually be CHEAPER that codestone training. If you want to reach 700 boosts in both Str and Def you may have to lay off the lab for a bit while you train. If your goal was to abuse the NCW leagues with a low-boost, high def pet, then you will have to start over.
Now, I'm going to just assume that your goal is just to have the best overall pet you can, for the lowest amount of NP in my recommendations.
With that in mind I recommend the following
1. Use the Swashbuckling Academy to train Level up to 40. Dubloons are a lot cheaper than codestones, and long-term lab use produces a net loss in levels.
2. Once you get to level 40, Start scratching 5 Terror Trove Scratchcards a day. They have a small chance to give levels as a prize, and on average this is a slightly cheaper method of gaining levels than spending 3 codestones for them.
3. Your immediate goal is to get to level 50, as berserk attack can be big, so you may want to use some codestones to get there during wars, but in general the average level gain from 5 Terror Troves/day will more than offset the average loss from the lab ray
4. Your long term goal is to start gaining Str and Defense to catch up to hit points.
4a. If you want to do this at the training schools it is going to take a lot of time and a pretty immense outlay of neopoints. Going this route is going to require either laying off the lab for a year or so (which I don't like) or a pretty immense outlay of NP as you train to "race" the lab before it pushes your HP up into the range where your training costs increase even further (I don't like the costs of doing this unless your income is well over 100k/day or you have 10mil+ to spend on training when you start)
4b. But if you are patient, you can do this in a cheaper, slower, more frustrating method ( just like me!

). In this case, you have to use all the alternative training methods to your advantage. Visit Coltzan's shrine every 12 hours, he does give free stats (and gave me both the 20 boost and my new 35 boost in defense this year). Visit Turmaculous as often as you can, he can give Strength points for free. Do kitchen quests: set a price cap on what you have to spend on training and pass on any that cost more than that; but until you hit the 10/day max make sure you are always doing a K-quest (or letting one expire). Make sure never to pass on faerie quests, and cross your fingers for the other random events which can raise stats. This is slow going, but far from hopeless, even with my two pets, K-Quests, F-quests, Random Events and Coltzan's Shrine have produced a net gain (after lab losses) of 30 points of defense on my lab pet since Jan 1st 2007.