1 option is to back out... is that something you are considering? Of course depends on where you are in the process (ie does your accepted offer allow backing out per inspection or appraisal?). If you are past the inspection and appraisal, you could technically back out before closing BUT that doesn't look good!!
The other option is to reduce the projected repair cost as much as possible, and focus on increasing the ARV as much as possible. Investigate how appraisers in your area value houses and use that to your advantage... sq ft, bd / ba count, materials used in kitchen or bath, etc ... I haven't done this myself but are all examples I've hear with success in the forums depending on how appraisals work in your area. For example, if home values increase greatly just by having luxury tile in the bathrooms, do that!
Is there something creative you can do with the property to have higher ARV? Can you target finding cheaper / used materials on FB marketplace, craigslist?