4. Bring a backup for Mane and Firmino
Just as the full-backs, the trio of Mane, Firmino and Salh will not be replaced anytime soon. Also like their defensive counterparts, they do not have competent backup to put themselves on the scoresheet if any of the three misses a game. On the right side, Shaqiri has proven his value and definitely is a worthy replacement.
Origi and Sturridge do not cut it at such a high level and at least one of them has to leave the club at the end of the season. A player who is able to play on the left and in the center of attack would be perfect. This profile is quite difficult to find and usually consists of players that are too good to only be second choice.
Ante Rebic is the first option for this profile. The Croatian international plays for Eintracht Frankfurt in the Bundesliga. He is listed as a left-midfielder in both squads but already played 70 games in the forward or second striker position. He is a big threat on the counter and plays also quite aggressive off the ball, with an average of 2.2 fouls per game.
Despite that, Rebic copes quite well with the ball on his feet, dribbling 2 opponents a game, as well as making 2.1 shots and 1 key pass in the same time. Where he lacks the most is his passing: Only 56% of 15.6 passes per 90 reach the teammate. This poor number could also be due to the playing style of Frankfurt, as they very often play risky through balls to their offensive guns.
The other player making the list is Diogo Jota. He already participated in 10 goals in his first Premier League season. He usually starts from the left-wing, but also has a history in the center forward position, where he played around 50 games of his young career. He might be less dangerous than Rebic with "only" 1.4 shots and 0.9 key passes per 90 to his name. However, the Wolves player is superior on the ball as he manages to get a 73.2% passing accuracy, while making around 22 passes a game.
Both of these players are valued around £40 million and depending on what Klopp is looking for, definitely worth a look at.