Importing positions previously created using DeFi Saver to ETH Saver is an included feature and allows anyone to move existing leveraged staking positions to this new interface and new fee model.
Once you connect your wallet at https://ethsaver.com/ the interface will display any supported positions that you already have at DeFi Saver and simply provide you with an Import button.
Since ETH Saver uses a performance based fee model, note that your position's balance at the moment of importing will be considered its starting balance. and the performance fee will only be applied to any profit from that moment onwards.
Please note that there is currently no way to export a position back to DeFi Saver once imported to ETH Saver.