I think 4.7% is optimistic for a 1040 brew. A typical final gravity of 1010 would give you 3.9%. 1013 is not unusual, and I don't think adding yeast is the answer. How long has it been in the fermenter? I would try to get it up to 20-22C and wait longer, unless it's already been fermenting for 4 weeks.
Also, too many homebrewers are obsessed with achieving a high alcohol content by getting the FG down as low as possible. This is bit complicated, because you do need the yeast to fully attenuate (consume all the available sugars it is capable of consuming) before you bottle or keg, or your priming/carbonation will be all wrong, as it is likely that any sugars that were not consumed will be consumed in the bottle/keg, and the beer will be become over-carbonated.
However, the percentage of sugars in a beer that any given yeast can convert to alcohol varies according to what grains and extracts are in it. Brewers deliberately vary this to make beers with varying dryness/sweetness. So they use different grains and extracts, and different yeasts, to achieve a desired level of sweetness. And they also calculate the amount of base malt or extract required to achieve the desired ABV. A FG of 1014 may provide a good level of sweetness. You can add extract to boost the ABV.
With kits, the only ways you can alter things are to add extracts, use steeping grains, or use a different yeast. Nottingham and US-05 generally consume about 80% of the sugars available. Windsor yeast only around 70% - leaving more sweetness/maltiness behind, which many people like. They can adjust the ABV with extra malt or sugar.
