An improvement, or betterment, extends the useful life of the property or one of its systems, or adds value to the property. A repair restores the property to as-is or as-was condition. Classical improvements are things like a new roof, replacement windows, or remodeling the kitchen. Classical repairs are things like painting, or fixing a hole the roof (without replacing the whole thing) or replacing broken kitchen cabinet doors with matching doors because of tenant damage.
I think this situation could be argued either way. On one hand, it's probably a long term problem that happened over time, and the work is needed to keep the property standing; on the other hand, you aren't remediating the entire foundation, just selected elements that have failed. I think you can take it either way.
