1. Safety: Taylor Mays shouldn't be starting, and Clements and Crocker are still both free agents. Cincinnati needs to bring in at least one safety early in the draft. They will probably take one with their first round pick or the early second round pick they have from Oakland.
2. Right Tackle: It doesn't look like the Bengals are interested in bringing back Smith despite all of their cap room. That said, they will probably look to replace him in the first two rounds of the draft, mostly likely the second round. If they valued the position enough to use a first round pick on it, they probably would have just brought back Smith.
3. Running Back: The Law Firm is a decent back, but he needs to be paired with someone to be as effective as he can be. There will probably be a nice group of backs available in the third and fourth rounds for Cincinnati to choose from.
4. Linebacker: Cincinnati needs someone to replace Lawson, who signed with Buffalo. They will probably try to address this with a mid round pick, or even as early as the second round. Te'o would be an interesting option if he fell to them.
5. Wide Receiver: I think Sanu will develop into a solid #2 receiver, but you can't bet on that. The Bengals might want to use a later selection on a wideout with some good potential. They should help Dalton continue to develop as much as possible.
6. Center: The Bengals have a fairly large selection of people on their roster who are capable of playing center, but none of them are going to give you a long term solution. If a good center falls to them in the draft, don't be surprised if they scoop him up, even if it's in the middle rounds.