I think you must be bringing them inside with your plants when they come in for winter. I also have many, many houseplants that summer outside but I have never had an aphid problem indoors. Treating the plants and rinsing/spraying them thoroughly before bringing inside should reduce any insect issues to close to zero. Then you just monitor daily or as often as you can manage.

For now, I might opt for an indoor houseplant systemic - Bonide or Bayer BioAdvanced.

I have never had aphids on houseplants but I do bring in other flowerings plants indoors to overwinter and have had some aphid outbreaks, luckily none this year except on a couple of mums. Aprt from what GG has suggested you can also try home made horticulture oil (1-2% baby oil in a gallon water plus a few drops of dish soap). Use one the gallon/half gallon pump sprayer rather than a spray bottle to make life easier. Another option is to get lace wing larvae or lady bugs. One year I bought some live lady bugs (several hundred or a thousand, I can't remember but they came in a large soup plastic container with a mesh lid and interspersed with wood shavings). I released them in batches (keep rest in the fridge). It was fun, they tended to be attracted by grow lights and also try to escape via window corners. I am not sure how much aphids they ate (the problem dissipated on its own) but I had a lady bugs go on to breed on one of my clematis, there were eggs and then cute little larvaes. They usually stay on the plants or windows and are not a bother for the most part. I understand that lace wind larvae are the most efficient biological aphid control.

I always end up with aphid problems indoors. In December I'm optimistic I can wash and crush my way through an infestation, but by January and February they begin to show up on everything and eventually I'm overwhelmed. It always starts on one of the 'buggier' things I bring in. This year i went through the milder steps, then insecticidal soaps, then some premixed sevin, and then finally resorted to one of the Bayer products with imidacloprid. I found that if I spray the buggiest plants with that, the aphids are easily controlled on the other less attractive plants.