A photo would help, but if the tip is healthy it would be better to take a cutting from that and root it to start over.

Here's a photo. I've never done a cutting before, what would I need to do exactly? There are several branches splitting off from this one branch at the bottom. Should I try taking multiple cuttings? Many thanks!

Good at least there is some branching I was picturing one long stem from your description. Also there are more leafy sections than I was picturing. Anyway the plant also looks like it could use more light, but depending on where you are that may rectify itself with longer days and summer sun. If you do increase the light do it gradually, a little more each day, or you will sunburn the plant (it will bleach out). Before you do any of that though try some cuttings. The cuttings will root easiest under artificial light......if you have a "shop light" with a pair of fluorescent bulbs that is great assuming you can keep the pot a few inches below the light. Else a bright windowsill would be good (but not much/any direct sun, just bright) for rooting the cuttings. The area should be warm....not hot but warmer room temp say 70-80 best. For the cutting itself you will need a clean pot (you can also use a plastic drinking cup with a drainage hole poked in). Get some good sterile potting soil and add some extra perlite to it. Mix it and moisten it but let extra moisture drain out. For the cuttings you can use all the branches. You are only cutting the tip.....say 5-6" or so with green stem and a couple leaves. Make nice clean cuts on a slight angle (e.g. with a new razor). Pull off the bottom leaf or two (leave a couple leaves on the growing end) and stick the other end into the potting mix. You can lightly pinch around the cutting so that there is good contact of the cutting and mix. YOu can then put the cuttings and pot into a clear plastic Ziploc bag and under your lights (sunlight will cook them, that is why fluorescent lights are good). After a week or two gradually open the bag a little more each day. They should root in a couple of weeks. In the meantime keep growing the mother/original plant......it will make new branches at each of the cuts.

Thank you so much! that's great. And indeed my apartment gets almost no direct light. So I've been augmenting with a grow light. I have a backyard that gets direct light but I'm afraid of it getting blown around and broken. If you have any advice for how to prevent that let me know. you are clearly a plant genius. thanks.

Where in the world are you?? E.g. are you in Florida or Minnesota or ?.... The original plant would probably have trouble out in the open, but once the cuttings are rooted and SLOWLY acclimated to sunlight and outdoor conditions they will probably do well outside during the summer season as long as you remember to water regularly as needed. They will grow thicker stockier stems and branch more readily.