The US census has been completed last year and is currently being processed. As a result, states will gain/lose/hold electoral votes and hence members of their congressional delegation. Do states still have to redraw their districts if this number stays the same?
Generally, yes. Even when a state keeps the same number of congressional districts, people might have moved around the state. Districts have to all be approximately equal in population, so when the new census figures come out the state has to make sure that they're still approximately equal. If they're not, the state has to change them so they are.