Kepa was signed in the summer of 2018 from La Liga outfit Athletic Bilbao for a fee of £71m, but he is yet to justify his price tag as the most expensive goalkeeper in the world despite having a fairly decent first season under Maurizio Sarri.
The Spain international has recently come under intense criticism for letting in goals against Newcastle United and Arsenal.
Kepa has kept just five clean sheets out of his 24 Premier League appearances and has conceded 32 goals this season.
Chelsea have been linked with a number of goalkeepers to replace the Spaniard, which includes Burnley’s Nick Pope.
Ahead of the Blues’ visit to the KC Stadium to face Hull City in the FA Cup fourth-round, Lampard said he is not aiming to sign a goalkeeper in January but insists Kepa must arrest his poor form.
The former Derby County head coach confirmed Caballero, who has played in cup competitions this season, will replace Kepa against Hull and claimed the 38-year-old will have the chance to keep his place with a good display.
"I'm not looking at signing a goalkeeper now," the English coach told BBC Sport.
"I'm aware of the criticism, but I'm not affected by it.”
"Kepa knows there have been mistakes that have cost goals. That's the nature of it and that needs to improve."
