In my opinion 15 years and 200,000+ miles is plenty of life to have gotten out of a car. All the issues you described are pretty classic old car problems. You mention more kids on the way, as in babies. I'm sure the vast majority here will argue you need to just keep this car forever and never buy a car again, switch to cycling and walking, etc but I'll be the outlier and say that this is potentially a good time to just go with a new car.
Now hear me out: generally that's a bad idea but you must have seen the same thing I've seen going on, which is that used car values are stupid right now. A friend of mine just sold his 1 year old Civic Si for slightly more than he paid for it new. Now that was a somewhat special case, in that Honda has discontinued the Si coupe entirely, so there simply isn't any way for people to buy a new Civic Si coupe but it highlights with an anecdote the absolute nonsense going on with used cars right now.
Meanwhile used cars, especially plain old sedans, are still getting discounted around my parts. Everybody wants trucks and SUVs so if you're willing to go for another Civic sedan, or a Corolla, any sedan or hatchback/wagon from Hyundai/Kia, or really just about anything "sedan" you can likely get a discount, low to 0% financing, and a higher than normal amount for your used car in trade. Keep that next brand new car for another 15 years and you'll have well and truly gotten your money out of that car too. This is kind of how I've done it, and I'm in my mid 40s having bought only 3 (economy) cars in my life so far, making cars a pretty minimal expense for what will have worked out to possibly all my working life by the time I am done with my current one.
Car accidents are generally the leading accidental cause of death for a huge number of our years on this planet, so for safety alone I think it's worth at least trying to keep cars to 10-15 years and newer, especially while your kids are very young and vulnerable.