As @GershonGold said, an Orthodox rabbi would not approve your husband's conversion while he is still married to you, and he would not re-marry you afterward, because doing either of these would create an inter-marriage that is a violation of halacha.
One possibility is Isaac's from the comments; he could look into Noachide options. Another is this: the two of you could study for conversion together, knowing that conversion won't happen until and unless you're both ready. Meanwhile, he can begin to practice, you can explore what that means for you, and maybe you'll become more interested over time. You said you don't know if you want to convert, not that you know you don't, else I wouldn't suggest it.
I knew an Orthodox rabbi who had some students for many years (10+), and not all who study for conversion will ultimately convert. So it wouldn't be wrong for you to start down that path, so long as you're completely up-front about your current thinking. Converting is a big step and when you're at the beginning of the process you don't know enough yet to make an informed decision -- that's part of what the rest of the process is for.