The older, the more stressed a plant is the less they will be able to 'bounce back' from pruning. This plant is a vine. I am not at all sure what it is you expect of the base, usually, vines at the base are bare; lack of sun, better leaves at the ends of the vines that get great light. That is the cool thing being a vine,the plant can 'travel' to find the best light.
I would leave this plant alone. For one thing, your plant is getting fairly old for this species. There are ways to invigorate your plant without pruning drastically. Have you ever fertilized? With a balanced fertilizer? Have you re potted this plant in a larger pot with potting soil (sterilized bagged soil)?
What I do for my indoor plants that are also called medium term perishables, is to take them out of doors on a covered porch for the summer. Makes them a 'long term perishable'...No direct sunlight. Lots of hosing them down washing insects and dusts off the plants. This extra light helps your plants make more food for themselves to last through the winter. I would also repot them in fresh sterilized soil, no rocks or gravel beneath the soil. Giving them a balanced fertilizer once or twice a year. Do not over water. Lots of blowing air...from a fan or open windows.
Your vine could use a fresh up pot. 2-3" larger pot, sterilized potting soil, south facing window for winter and out of doors on a covered patio so it gets more light, makes more food for itself, thus being able to last the winter months better.
Where I live this plant is an annual. Even indoors, after one year an annual that has been able to produce seed, just gives up. You've an exceptional environment. I have a feeling that you've done an exceptional job with this plant.
Annuals are one season plants...their entire focus and purpose in life is to make seed. Lots of flowers equals lots of seed. Once an annual produces seed, its job is done.
I am thinking you should get a fresh, young plant to replace. Gather its seed and try to start a new plant from the seed.
There are easy ways to control aphids other than drastic pruning. Have you used garden soil in this pot? Is this plant out of doors?
We need much more information and definitely pictures. You might have spider mite going on, I am assuming you know what aphids look like by now. I just imagine this plant being out of doors, is it?
You most certainly can cut off dead stems, branches, leaves from your plant. I just hope you don't cut a bare stem to find it is the main stem for your plant. Please send pictures and more information. This answer is just to help you to tell us and show us more about your plant and situation. Grins! Maybe I've assumed correctly~