Question on position sizing with partial closes

Been trying to get a handle on more advanced position sizing, specifically when it comes to partial closes. If I open a position at say, 1% risk, and then close half of it for a gain, does the remaining half still count as 0.5% of my initial risk, or should I be re-evaluating the risk on the remaining portion based on its new stop and my current account balance? I'm finding my spreadsheet gets messy tracking the original risk versus the effective risk on the remaining portion. How do experienced traders typically account for this without overcomplicating things?