wlan vs lan rewiring

case layout:

1)factory layout 100m witdh * 200m lenght
(office are double storey)
2)automotive part (poduction area has same high as 2 floor office)
are produce in the center layout leaving 15m lenght at every end for office
3)currently installed are lan cables that are 8 years old (all over)
4)3 cisco 54mbps ap are newly installed (signal are bad may be from factory’s EMI)

case objective:

1)should i rewired all the cablings?
2)should i convert to wlan where the signals are quite busted
3)consider the wlan trial led to messary becouse of signal lost and client unsatisfictory
4)budget constrain
5)top level approch

what should i do to please every one?