Your post is a little unclear. This is what I gathered: you sued your sister to evict her, you paid an attorney $1,000 to do so. Your sister countersued saying that you made an oral offer to sell her the property. You don't say whether your sister claims she ever accepted that offer. Now the attorney wants another $1,000 even though you feel like nothing has been done in six months?
You and your attorney should have signed a fee and representation agreeement which outlined the terms of how you would be charged. I'm assuming that the attorney is charging you by the hourly at an hourly rate and the $1,000 was an advanced fee retainer for her to bill against her time. When the retainer is exhausted, the contract or the practice is that the client replenishes the retainer which sits in a trust account. If there is anything left in the trust account when the matter is concluded, the remainder of the funds is returned to you.
If that is your arrangement, your attorney should be sending you a regular invoice (most attorneys send monthly invoices) that account for her time and how much time she's billed against your retainer. If you don't know what she's done in six months to earn the first $1,000, ask her for an invoice showing her time. That might clear things up for you.
If you're question is really is it reasonable to expect to spend $2,000 in an eviction in which the tenant files such a counterclaim, my answer is yes. Especially if the fee agreement is such that the retainer was also to cover any filing fees. The filing fee to file the complaint, attorney time drafting a complaint and an Answer to your sister's Counterclaim, attendence to the first cause of action hearing (eviction hearing), and regularly phone calls and correspondences to you could very easily equal $1,000 in costs and attorney billable time.
Like any other contractual dispute, a dispute with your attorney about fees starts and ends with the parties fee agreement, which should always be in writing to avoid these kinds of otherwise avoidable disputes in the first place.