Yes, drill-and-fill. The crew drills 2-inch holes between studs, injects closed-cell foam (or pour-in cellulose for budget jobs), and patches. About 90% as effective as open-wall foam at 60% of the cost.
More detail
Drill-and-fill (also called injection foam) is the standard retrofit method when the homeowner wants to upgrade wall insulation without removing siding or drywall. The process: locate cavity centers between studs using stud-finder and confirmation drilling, drill 2-inch access holes near the top of each cavity (interior side typical for finished homes; exterior side when re-siding), inject expanding foam through the hole using a flexible nozzle that reaches every corner, fill until the cavity is full, patch the hole with drywall plug and skim coat. Patching adds modest labor cost but the patches are invisible after texture and paint match. Effective R-value runs roughly 90% of open-wall foam application because of cavity irregularities (electrical wiring, plumbing, blocking) that slow injection coverage. Cost per cavity is roughly 60% of open-wall foam, which makes drill-and-fill the right choice for most Cincinnati retrofit projects where the walls are otherwise in good shape. Cincinnati drill-and-fill cost-vs-effectiveness math: typical pre-1980 wall-cavity foam retrofit runs $5-$8 per sqft of wall area for drill-and-fill closed-cell, including patching. The same project at 90-95% effectiveness of open-wall foam, at roughly 60% the cost. For homeowners not planning to re-side or remodel exterior walls, drill-and-fill is the practical retrofit method.