Reja's men go into the match at Catania on the back of last Sunday's 3-1 defeat to Bologna.
The result marked Lazio's first league loss at the Stadio Olimpico since November.
Despite the setback, the Biancoceleste held on to third place and the last Champions League qualifying position because Udinese lost 1-0 at Novara.
"The only positive is that we are still third," Reja said. "But we played badly.
"We accept the criticisms and try to improve at Catania."
Lazio are two points clear of closest rivals Napoli and Udinese, who square off at the Friuli stadium this weekend.
A draw in Udine would benefit Lazio provided the Romans win at Catania.
"We just have to focus on ourselves," Reja said. "We need to get as many points as possible and we cannot have the wrong approach.
"It's difficult to get points at Catania but if my team reacts in a positive way then I'm convinced we can bring home three points."
Catania are one win away from defending their Serie A status and goalkeeper Juan Pablo Carrizo is confident that result will come.
Vincenzo Montella's side followed their goalless draw at Cesena with last weekend's 1-0 triumph over Fiorentina.
The win allowed Catania to increase the gap over the drop zone to 13 points.
Catania are eighth and two points away from reaching the 40-point mark, a figure deemed sufficient to retain their place in the top flight.
"We take on Lazio ready to claim a win in order to get to our first aim, that of defending our Serie A status," Carrizo said.
"We know it's going to be hard because Lazio play well but we are ready."
Lazio will be without midfielders Francelino Matuzalem and Alvaro Gonzalez, both suspended.