As has been mentioned this is not straightforward. But you do have options.
- Check with Vendor and get update
- if you have source you can try to update yourself.
I don't agree that it is neccesarily too complicated to upgrade. Delphi 2009 did add (finally - about a decade after it should have) very good Unicode support into the heart of delphi, but this was done down to the level of almost every built in function.
We upgraded a large (700,000 lines) project in only a couple of days. There is info on the net on what to do, there are a number of functions you need to replace if you use them (such as any funcion with Ansi in the title). Its worth a try at least.
If you dont have the source I'm afraid you have no choice but to contact the vendor, there is nothing you can do since the binary format for each Delphi version is differnt.