OP, if you want to just focus on hard numbers, look at it this way. You've owned the vehicle for 14 years and 215K miles, and put $3400+2500 of non-routine maintenance/repairs into it. That works out to $421.00 per year. Can you own a "new, maintenance free" vehicle for that? Doubtful. Even if you prorate your maintenance expenses over the last 100K miles, it only amounts to about $1000/year. Still less than the payments on a new vehicle.
The most expensive part of owning a vehicle is the depreciation in value in the first 5-7 years. You've already gone through that and paid that price. Now's the time to enjoy the fruits of your patience. This is the cheap part of your transportation strategy.
If you don't like the vehicle anymore, by all means trade it for a different (newer?) one. But you likely won't save money by doing that.