url[userID_, page_] := StringJoin[
  "https://api.stackexchange.com/2.2/users/",
  ToString[userID],
  "/reputation?page=",
  ToString[page],
  "&pagesize=100&site=mathematica&filter=!9YdnSQ3Rz"]
Needs["GeneralUtilities`"];
data[userID_, page_] := ToAssociations@Import[url[userID, page], "JSON"]
next[userID_][old_] := With[{new = data[userID, ToExpression[old["page"]] + 1]},
  <|
   "items" -> Join[old["items"], new["items"]],
   "page" -> new["page"],
   "has_more" -> new["has_more"]
   |>
  ]
res = NestWhile[
    next[121], <|"items" -> {}, "page" -> 0, "has_more" -> True|>,
    Slot["has_more"] &, 1, 10]["items"];

UnitStep[#] # &[DeleteMissing[
    res[[All, "reputation_change"]]
    ] - 200] // Total