Here is a work around that another user posted, not sure how well this works, but it may be worth a try;
Galaxy Forge work around;
Essentially, it would appear that SoaSE 1.15 does not need all of those normal & quick entries in the .galaxy file...just the "normal" ones. So, "fixing" the old map becomes a 3 step process for me that doesn't require anything but notepad and takes all of 3 minutes if you can type and have a decent rig.
Assuming you've opened your .galaxy file in notepad, perform the following:
1 - Manually edit the version number to "3".
2 - Use the "Edit" menu to open the "Replace" function. Find what: homePlanetUpgrade, Replace with: normalStartHomePlanetUpgrade. You can either replace the 5 occurrences individually or use Replace All to kill 'em all with one click.
3 - Again in the replace window, Find what: startingUpgradeLevel, Replace with: normalStartUpgradeLevel. This is the longer one, and it will take a bit to replace them all if you have a ginormous map or a slower rig.
Save the changes and load 'er up.