I have a script called OpenSesame which can be used to open AE projects in older versions, back to CS3. So you could apply the preset to a new project in your current version, use OpenSesame to export it, then reimport it into your earlier version of AE, select the keyframes, etc and save as a new preset in the older version.http://aescripts.com/pt_opensesame/
OpenSesame has a few limitations though. If your preset contains any "custom data values" (i.e. non numeric properties like Levels Histogram) then they can't be converted. Also the free trial version is limited so that it won't convert effects, so you'd have to use the full version I'm afraid.
Apart from that, I think your only option is to manually recreate the presets in the older version.