If you are not sure about your feelings don't get into it. If you are sure about your feelings there are two options: "Really, Oh My Gosh, I have feelings for you too." "Yea, good luck with that. I'm done."
My ex girlfriend told me that too, she's my girlfriend now . That's because I always had the same feelings for her, but the reason why she broke up with me before was because I was always active during self-harm, and she just lost those feelings from there. I'm now 12 days clean, and while dating another female, she realized she had those feelings back, and that girl broke up with me..
Getting out of that, if you still have feelings for her, give it a shot. Why not? It'd be best to know if you still love her or not if you want to reply in a nice way.
Did you like her back? If not don't say yes and be leading her on to only be let down harder. Sure it could be hard for her to get over at first but you don't want her to chase far fetched dreams that won't happen. If you did jump on it as fast as you can because if you get a second chance that may be the last and it shouldn't be taken lightly.