npm install showing up to date instead of installing the packages

I am having some trouble with npm install.

npm install package-name is working perfectly, but when I add a new dependency in the package.json file manually (by pulling via git) and then try to npm install only, it returns

up to date in 4.2 sec 

And doesn't install the package.

FYI: I am using git to pull the package.json file. So there is no any issue in the package name. It just doesn't work when i pull and try to install it with npm install only.

My package.json is:

{
  "name": "ap",
  "version": "0.0.0",
  "license": "MIT",
  "scripts": {
    "ng": "ng",
    "start": "ng serve",
    "build": "ng build",
    "test": "ng test",
    "lint": "ng lint",
    "e2e": "ng e2e"
  },
  "private": true,
  "dependencies": {
    "@angular/common": "^4.0.0",
    "@angular/compiler": "^4.0.0",
    "@angular/core": "^4.0.0",
    "@angular/forms": "^4.0.0",
    "@angular/http": "^4.0.0",
    "@angular/platform-browser": "^4.0.0",
    "@angular/platform-browser-dynamic": "^4.0.0",
    "@angular/platform-server": "^4.1.3",
    "@angular/router": "^4.0.0",
    "@ng-bootstrap/ng-bootstrap": "^1.0.0-alpha.26",
    "@ngx-translate/core": "^6.0.1",
    "@ngx-translate/http-loader": "0.0.3",
    "@types/underscore": "^1.8.0",
    "angular-datatables": "^4.1.0",
    "angular2-busy": "^2.0.4",
    "angular2-jwt": "^0.2.3",
    "angular2-toaster": "^4.0.0",
    "chart.js": "^2.6.0",
    "core-js": "^2.4.1",
    "datatables.net": "^1.10.15",
    "datatables.net-dt": "^1.10.15",
    "jquery": "^3.2.1",
    "ng2-charts": "^1.5.0",
    "ng2-simple-timer": "^1.3.1",
    "rxjs": "^5.1.0",
    "underscore": "^1.8.3",
    "zone.js": "^0.8.4"
  },
  "devDependencies": {
    "@angular/animations": "^4.1.3",
    "@angular/cli": "1.0.4",
    "@angular/compiler-cli": "^4.0.0",
    "@types/datatables.net": "^1.10.1",
    "@types/jasmine": "2.5.38",
    "@types/jquery": "^2.0.45",
    "@types/node": "~6.0.60",
    "codelyzer": "~2.0.0",
    "jasmine-core": "~2.5.2",
    "jasmine-spec-reporter": "~3.2.0",
    "karma": "~1.4.1",
    "karma-chrome-launcher": "~2.1.1",
    "karma-cli": "~1.0.1",
    "karma-coverage-istanbul-reporter": "^0.2.0",
    "karma-jasmine": "~1.1.0",
    "karma-jasmine-html-reporter": "^0.2.2",
    "protractor": "~5.1.0",
    "ts-node": "~2.0.0",
    "tslint": "~4.5.0",
    "typescript": "~2.2.0"
  }
}

via hunzaboy