If the plane fits your mission there is no sense in changing models.
You buy at retail and sell at wholesale and there are taxes involved in
purchasing. Now that you have fixed it up, keep it. OTOH, if you want
to buy a simpler less expensive plane or a more complicated faster one,
then trade. Like you say with old planes, everything is, on average,
half worn out. One place you can maybe save is to do your own oil
changes and simple maintenance. Also, if any avionics are not being
used or appreciated, take them out when they break instead of repairing
them. Other than that, it is luck and who you have as a mechanic. Right
now the small aircraft market is in a bit of a slump. So it's a good
time to buy, a bad time to sell.