Such posts are always a venue to learn a lot and sometimes hurt a lot. Don't give up. Yes, critters sometimes can have the amazing ability to go some distance. Always learn from these experiences. They teach you a lot. Stay firm in your resolve.
Start doing a grid or circles around the last point of blood found. Winter hides can suck up a lot of blood, especially if you hit center or high of center. Good chance the body cavity filled up and the deer is down.
Use all your senses to review the data. Did you smell the arrow for stomach (arrow can look clean but has the pungent smell). Did you visualise the hit in relation to the anatomy amongst other things.
Beware, there is a no mans land just above the lungs and under the spine which causes a lot of grief. Although smaller in deer, it does exist. So really visualize the hit and consider the angles taken. If you hit a little back of high center on a slightly quartering forward and uphill shot, guess what you have. Don't give up until you have eliminated all possibilities. In some cases, a no mans land hit may find the deer walking some days/weeks later.
PS, I found one on a similar hit. Made a high hit, flat ground, 90degrees, hit on a mulie in snow. From the shot, it hit 4" high from center chest. Upon inspection very little blood on the arrow fletch, otherise clean. Followed tracks, no blood, then a spec, then a couple more specs about 50 yards down trail. But without snow would have been impossible to follow. Deer went at least 200 yards. I knew where the deer fell by sound.
IMO, your best hits are always bottom third on flat ground. That changes a lot depending on shot angle and slope. You have to tailor the shot to the anatomy of the animal on any given angle or slope. 3D targets train you improperly.
Hope you find this one. If you hunt enough, this S#$t happens. Learn from these times.
Elky....