When I use 301 redirects for all URLs ... should i change sitemap URLs ??? ...... e.g: Sitemap contains bellow URLs
example.com/cat/1.html example.com/cat/2.html example.com/cat/3.html
Should i change sitemaps URLs to new Destination?
example.com/cat/year/1.html example.com/cat/year/2.html example.com/cat/year/3.html
Yes, change them to the new URLs. Although the 301 redirects tell the search engines where to find moved pages you shouldn't be feeding them inaccurate information about your web pages. Besides possibly being error prone, it may also be an indicator of quality. While this may not affect your rankings, it may possibly affect crawl rate and other related things. If it is in your power to provide an accurate sitemap, you should do so.