If you're just looking for someone to spoon-feed you a number, you can skip the rest of this.
So you're asking, essentially, how much money you'll need to re-make your game. That it's going on Kickstarter is irrelevant, because games get funded there asking for anything from several hundred dollars to several million. You just need to be honest about what it will take to make the game (which it sounds like will be largely dependent on what rate you can hire people for, and how long those people will take to make the product), and ask for that (plus ~20% for taxes and fees).
Another thing to consider and add in to your total is cost for production of any reward-tier items. A lot of Kickstarter projects give incentive gifts for larger donations, with the idea that part of the large donation will be eaten in manufacturing things like collector's edition packaging, figures, and other game-related kitsch.
The issue is still the same, though: the number will be very specific to your project. Obviously lower goal amounts have a higher chance of getting funded, and looking at the fact that your game is
a) already created (just needing a new UI and graphics component), and
b) not overly-ambitious in its scope (you're not making a WoW-killer or epic 80-hour FPS)
if I saw a goal at or over 80k (USD) I would think you were asking for way too much (just my opinion though, I'm no marketing specialist). You're really just in need of some new graphics assets, if I understand the post correctly, so you'd only be picking up one or two other people? The re-make just doesn't appear like it is particularly taxing on anyone's resources.