Contrary to popular belief, the Christian hope is for Jesus to return to the earth (Acts 1:11), for him to raise the dead (1Thess. 4:16; 1Cor. 15:20-23; the resurrection) and make his faithful followers immortal (Rom. 2:6,16), and for the world to then be made perfect (Rom. 8:18-21). Put bluntly, people do not go to heaven (John 3:13; Acts 2:29, 34-35). It would be truer to say that, eventually, Heaven will come to earth (Rev. 21:2-3; for more info, see Where will the Kingdom of God be — in heaven or on earth?).
When the Kingdom of God is set up on earth, there will be plenty for the immortal saints to do. In Revelation it says the following about what the saints will be doing in the kingdom:
you [Jesus] have made them [the saints] a kingdom and priests to our God, and they shall reign on the earth. [Rev. 5:10]
This means that, in some way, the saints will be at work as rulers and as priests, helping Jesus govern the world (cf. 1Cor. 15:24-26) and, as priests, teaching the mortal population about God (for more info on the mortal population of the kingdom, see Who will be living on the new earth?). It will be a busy time, for sure.