I have Kelieh, and have gone from passive, then to bi-active, and then to tri-activ. I have to tell you that as far as bang for the buck, going Aktiv is the only sound choice. At minimum, with what you have in the 85 and 140, I would recommend three possibilities.
1) Bi-wire the Keilidhs. Go bi-aktiv with the amps you have. Treble on the 140, bass on the 85. This will be the cheapest thing that you can do, and will sound tons better than switching from the 85 to another 140 and remaining passive.
2) Go tri-activ, which is my setup. You can put treble on the 140. Then by another 85, and go first bass in one 85 and second base in the other. For this you have to setup the speakers for tri-wire.
3) The other option is to sell the 85 and get two 140s, and then go tri-activ with all 140 for treble and bass. I don't think you need to do that. If and when you go tri-aktiv, the 85s on the bass channels will be very good.
So, to put it into steps, I'd suggest you have a treble aktiv cards installed in the 140 and bass card in the 85 and have the Keliedhs bi-wired. Then later on you can add another 85 with aktiv card and have the Keliedhs rewired for tri-wire aktiv.
Hope this helps.