That will depend on your vision about the game, if you only play poker for fun or as a business or a way to earn some extra money, if you want to dedicate 100% to poker your bankroll is the most important thing accompanied by discipline.
Regarding your question, of course, you should increase your bankroll to be able to play more with a greater volume of play and be able to endure bad spells a little longer or perhaps if you want to level up and you need to repower your bankroll.
The first goal is to increase the bankroll, so you can play comfortably (maybe bigger) tournaments on regular basis. You won once now, so you can win again, no?
For sure, if it is a really big win, you should withdraw the most and leave enough for playing more.
Everyone has their own opinion on winning and whether or not they continue to play higher stakes or not. If you are playing for fun then I cash out 75% of my poker winnings leaving 25% of it to continue playing it. If I'm taking the game more seriously, I would try to increase my winnings to the next level of stake and make sure I keep to my bankroll management intact.