2012R2 - Hyper-V replica size on a single VM balloons daily

I'm having an odd issue that just cropped up with Hyper-V replica. I have 5 VMs on two hosts replicating to an offsite host.  Each of them are setup properly, with a dedicated paging drive that is not being replicated. Replicas typically take a few seconds to a few minutes, and I have not had this problem in the past year and a half since implementing. 
One of these servers is a 2012 file server hosting about 600GB of data, with deduplication running overnight.  A few days ago I noticed the replication state was "Critical".  I kicked of a resync, and it would get to 30 or 40% and then stop.  I removed the replication and re-added it, let the initial replica finish, then the resync, then it started replicating fine.  The next morning the state was "critical" again, and it showed that it had 25GB it needed to replicate.  This took several hours, it finished, then the next morning it needed 18GB.  It also wanted to kick off another resync, which took all day.  Now every 12 hours or so the replication is falling behind (as of right now it says it needs to replicate 25GB).  The odd thing is that this server is only adding or modifying 2GB to 3GB daily, and I am stumped as to why the replica sizes are so big.  The servers are all healthy.