After Clash of the Titans arc (from chapter 35 to chapter 50), it was confirmed that Reiner and Bertolt survived. Since they were previously planning to go back to their village with Eren, now that Eren has been rescued, will they really go back without Eren? Or will they come back for him?
After the Clash of Titans arc, we don't hear from the two again until right at the end of chapter 70, where we see Bertolt atop the defeated form of Reiner's Armored Titan:
After this, his opponent (the Beast Titan) shifts out of his Titan form and confirms their objective - that they indeed cannot return without what they came for; Eren, or the coordinate with the phrase,
"Reclaiming the coordinate should be prioritised, right?"
After this, the chapter ends with the Beast Titan's shifter gazing over the ruins of the Shiganshina district:
The trio, including Reiner and Bertolt are left lying in wait for the Survey Corps at this location, as they know that will try and retake Wall Maria and gain access to Eren's basement. Chapter 72 finishes with the Survey Corps heading back to Wall Maria, with the two shown camping atop the walls of Shiganshina. A meeting between both groups will likely occur in the next chapter, where we will be able to see exactly what they have in store for Eren.