Your assessed value has no bearing on the true market value of the property, only its value in relationship to other properties in the taxing authority's jurisdiction. Your taxes could go up or down as a result of the reassessment. It's not just the assessed value that counts, but also the applied millage, with the product of the two determining the tax. The local millage will be adjusted up or down immediately following a reassessment, then adjusted periodically (like annually) thereafter, usually only upwards, until the next assessment. Most taxing authorities will set the new millage so the total tax is "revenue neutral" immediately following the reassessments. (But of course that never lasts!) So at that point the total property tax revenue is unchanged, but some property owners pay more and some less, and many are about the same - or at least that's the story line!
In our local area the last reassessment about 10 years ago set the value of all properties for tax purposes at 50% of the market value (as determined by the assessors) at the time. The actual percentage is completely arbitrary. Those assessed values will remain constant until the next complete reassessment, which will probably be in about 15 more years. In theory, significant improvements or changes made to a property, like adding a garage or new addition, will cause a reassessment for that one property in the interim; those are triggered by building or zoniing permits.
The only real concern you might have at this point is how your property was assessed. i.e., was the correct formula applied, how does it compare to essentially identical properties, etc.? Assessed values are public record, and you should have access to the details of the assessment of your own property to make the comparison. You should also be concerned about how your property is currently zoned. If zoned commercial, for instance, you could be paying a much higher tax than for the same property that's zoned residential. But of course a commercial property has a much higher potential value as well. Incidentally, for taxation purposes the age and condition of the house, landscaping, improvements like the OP listed, etc., have little bearing on the assessed value. The formulas consider total square footage, number of rooms, garage or not, lot size, etc. as the major factors. (All those improvements can factor greatly into the appraised value of course, but not so much if at all in the assessed value.)
Period reassessments of all properties within a taxing jurisdiction are good. They help level the field so we are all paying fair amounts of property tax. But they also cost considerable taxpayer money to be performed, so they should only be done when a considerable imbalance is evident...