It is an interesting problem and one I went through myself with my previous 156. Some of the stuff you list is pretty much maintenance (Tyres, Disks and pads, bushes etc) so even if you buy a replacement car (assuming second hand here) you may end up having to spend similar money on the same stuff within the next 12 months anyway.
I would get a rough idea of what it is going to cost you to get all the work done on your car and then look at a replacement option and work out how the costs look. Don't forget any dealer is going to offer you sod all for your car as a trade-in. As you have looked after your car it is probably worth more to you that it ever will be as a trade in.
Good luck with your decision.