You ask an interesting and deep question -- one that has implications in qadar itself.
Let's start with the basics. From a long hadith in Imam Nawawi's famous collection of 40 (emphasis mine):
Verily the creation of each one of you is brought together in his
mother’s womb for forty days in the form of a nutfah (a drop), then he
becomes an alaqah (clot of blood) for a like period, then a mudghah
(morsel of flesh) for a like period, then there is sent to him the
angel who blows his soul into him and who is commanded with four
matters: to write down his rizq (sustenance), his life span, his
actions, and whether he will be happy or unhappy (i.e., whether or not
he will enter Paradise).
Simply put, Allah is Al-Aleem; he knows what actions you will take in your lifetime. Based on this, He obviously knows how long you will live or die.
There is also a hadith where one of ummuhaat al-mu'mineen made du'a for someone's life to be extended; Rasulullah replied that she's making du'a about "numbered days" (something fixed), and a du'a for forgiveness an salvation from Hellfire would be better.
On the other hand, there are ahadith like this one (emphasis mine):
Allah's Apostle said, "Whoever loves that he be granted more wealth
and that his lease of life be prolonged then he should keep good
relations with his Kith and kin." (Bukhari)
Scholars ask, how can you put these two hadith together? The wholistic understanding they came up with is simple: there are two levels of writing of qadar. There is qadar which is known only to Allah, and is writtein in Al-Law Al-Mahfoodh (the protected tablet). This is where your ultimate, final lifespan goes. And there's the qadar which Allah tells the angels, which may be your lifespan before accommodating for any changes for actions like keeping ties of kinship.
If you understand that, the rest of my answer actually addresses your answer.
Actions that increase your lifespan
As far as I can tell from my research, the only activity that increases your life is keeping ties of kinship with your relatives, as mentioned in the hadith above.
Actions that increase your rizq (wealth)
Having Taqwa of Allah: Allah says:
And whoever fears Allah - He will make for him a way out. And will
provide for him from where he does not expect. (Surah At-Talaq,
verses 2-3)
Istighfaar (seeking forgiveness from Allah): Allah says:
And (Nuh) said, 'Ask forgiveness of your Lord. Indeed, He is ever a
Perpetual Forgiver. He will send [rain from] the sky upon you in
[continuing] showers, and give you increase in wealth and children and
provide for you gardens and provide for you rivers. (Surah Nuh,
verses 10-12)
Tawakkul (putting your trust in Allah and taking the means): Umar ibn Al-Khattab said:
If you were to put your trust in Allah the way that Allah deserves,
then you would be provided for as the birds are; they leave in search
of food at the beginning of the day hungry, and they return at the end
of the day full. (Reference)
Fulfilling the Ties of Kinship/Family: The first hadith I mentioned from Bukhari:
Allah's Apostle said, "Whoever loves that he be granted more wealth
and that his lease of life be prolonged then he should keep good
relations with his Kith and kin." (Bukhari)
Being Thankful: Allah says:
And [remember] when your Lord proclaimed, 'If you are grateful, I will
surely increase you [in favor]; but if you deny, indeed, My punishment
is severe.'" (Surah Ibrahim, verse 7)
Frequently performing Hajj and Umrah: Rasulullah said:
Follow up between Hajj and Umrah (i.e. continually repeat the
performance) because they both eliminate poverty and sins just like a
furnace eliminates the dirty impurities of iron, gold and silver. And
an accepted Hajj has no reward less than paradise! (Tirmidhi)
And Allah knows best. Look up the book "15 Ways to Increase your Earnings (from the Qur'an and Sunnah) for a more comprehensive and detailed list.
