Does site update affects pagerank ?
 

Hi, I just made a new version for my site.
(it's not yet uploaded)

I want to ask these :
1) Will this, affect google's page rank for my site ? Right now, I have pr:4, and the h1,h2,h3 tags will be different.
Also, the pages titles, the metadescriptions and the main content (slightly) will be change. Will this affect my site's current position at search results?
2) Will i have to re-submit my new site to webmaster tools ?

It depends sometimes it may affect or sometimes it may not...

Sometime PR changes, sometime not

ok....Not very specific answers...
Will it increase it, or will it decrease my pagarank?

You have to worry bout two things here
1) On page SEO .. if you continue to improve your on-page SEO to the better that should improve your ranking
2) Off page SEO .. If you remove or deleted a page which has a backlink, the you might lose the backlink and that will reduce your ranking ..

You can keep the old one and start the new ones .. and once you get enough new stuff which worth good ranking then you can start deleting the old but slowly to get a feeling of the effect

Its not the actual Page Rank value you need to woory about. PR is one on-page factor amongst very many. What matters is the overall search engine performance. This is governed by the factors that are being discussed above and you making updates is a positive factor

Yes any updates in sites affects the pagerank.

It probably wont change the PR staus of your website and even if it does we wont know what it is because Google no longer publishes info on PR of sites.

However if you change headings and titles then your SERP rank could change. It all depends on if you optimize for different keywords or the same ones.