Did you want to continue with the same character? With DKS (original release or the
Developer's Cut version, with an added optional cheat mode and some other stuff) you can play from the remastered Ego Draconis part of the game, or start a new level 35 character at the beginning of FoV. Saves from the original release of D2:ED are not compatible (due to changes with the remastered version). You can re-create your character though, aside from equipment (which you would upgrade relatively soon, anyway) and inventory (you can easily replace alchemy and enchantment ingredients, and find/buy higher level charms and formula, etc). With a new FoV character your battle tower servants are picked randomly, but there are NPCs in Aleroth to perform those functions, as well.
FoV is still available separately (ie from
GamersGate). Since it requires a Securom key, you can use it to upgrade to D2:DC (see
Divinity 2: Developer's Cut and Anthology on Steam). If you are not really attached to your current character, though, it would probably be easier to just get D2:DC to start with (from the
Larian Vault, or GOG / Steam / etc), especially if you were going to play again anyway with a different build, etc.
