hello
You should have a directory with all the mxd's used for publishing but if not you should go to C:\arcgisserver\directories\arcgissystem\arcgisinput and get all the MXD's. For example C:\arcgisserver\directories\arcgissystem\arcgisinput\SERVICE1.MapServer\extracted\v101\service1.mxd
Put them in some temporary directory and republish them after a clean install.
If you change any parameters (for example number of instances) you will have to remember it.
You can get the model/python scripts in the same way for GpServices (even they usually a little different then original).
Image services you just have to check where the original image/mosaic is and republish.
A little work but not too much.
Have fun
Mody