More information would help. Given what there is, I don't think it is an easy choice. 2 additional 2nd round picks help. If you are weak at RB or WR, those two picks can plug some holes. Based on current FBG ADP for PPR, Kelce's ADP is 14. Your cost for Kelce of 2.12 implies some value with keeping Kelce. Henry's ADP is 63 or 6.3. I probably take Henry. Way too much value there and that 3rd 2nd rounder is more ammunition to pound RB/WR at the top of the draft.
I would also sort of look at it as comparing Kelce and a 12th round RB/WR with Henry and a 2nd round RB/WR. If you told me 40 RB and 40 WR are kept, and that extra 2nd rounder only gets you McCoy (RB39), Miles Sanders (RB40), Kupp(WR39), or Emanual Sanders (WR40), I would keep Kelce.