Add this to record_vars and take a took:

record(leverage=context.account.leverage)  

Use order_target_percent instead of order_percent to bring leverage down to 1

import quantopian.algorithm as algo  
from quantopian.pipeline import Pipeline  
from quantopian.pipeline.data.builtin import USEquityPricing  
from quantopian.pipeline.filters import Q1500US


import quantopian.algorithm as algo

def initialize(context):  
    context.x = symbol('JNJ')  
    context.y = symbol('HON')  
    context.term = 120  
    context.threshold = 1


    algo.schedule_function(  
        rebalance,  
        algo.date_rules.every_day(),  
        algo.time_rules.market_close(),  
    )  
    algo.schedule_function(  
        record_vars,  
        algo.date_rules.every_day(),  
        algo.time_rules.market_close(),  
    )


def rebalance(context, data):  
    pricex = data.history(context.x, fields="price", bar_count=context.term, frequency="1d")  
    pricey = data.history(context.y, fields="price", bar_count=context.term, frequency="1d")  
    pricex_mean = pricex.mean()  
    pricey_mean = pricey.mean() 

    beta = pricex_mean / pricey_mean  
    context.spread = pricex[-1] - pricey[-1] * beta 

    if context.spread > context.threshold:  
        if data.can_trade(context.x) and data.can_trade(context.y):  
            order_target_percent(context.x, -0.5)  
            order_target_percent(context.y, 0.5)

    elif context.spread < -context.threshold:  
        if data.can_trade(context.x) and data.can_trade(context.y):  
            order_target_percent(context.x, 0.5)  
            order_target_percent(context.y, -0.5)

    else:  
        pass 

def record_vars(context, data):  
    record(spread=context.spread)  
    record(leverage=context.account.leverage)

def handle_data(context, data):  
    pass